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"results": [
{
"id": 6695,
"topic": "gcn.circular",
"uuid": "afc569d4-98ce-490b-8a96-30e42ee4cc4f",
"title": "GRB 240418A: Swift/UVOT Upper Limits",
"submitter": "Hop gcn.circular",
"authors": "Sam Shilling at Lancaster University <shilling.sam@gmail.com>",
"data": {
"date": "24/04/19 16:06:19 GMT",
"from": "Sam Shilling at Lancaster University <shilling.sam@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36184"
},
"title": "GCN CIRCULAR",
"number": "36184",
"subject": "GRB 240418A: Swift/UVOT Upper Limits"
},
"message_text": "S. P. R. Shilling (Lancaster U.), S. R. Oates (Lancaster U.), A. A. Breeveld (UCL-MSSL), N. P. M. Kuin (UCL-MSSL) and M. H. Siegel (PSU)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 240418A\n126 s after the BAT trigger (Siegel et al., GCN Circ. 36162).\nNo optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 36166)\nis detected in the initial UVOT exposures.\nPreliminary 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first\nfinding chart (FC) exposure and subsequent exposures are:\n\nFilter T_start(s) T_stop(s) Exp(s) Mag\n\nwhite_FC 126 276 147 >20.6\nu_FC 284 533 246 >19.4\nwhite 126 5282 347 >21.1\nv 4072 4272 197 >19.3\nb 539 5093 216 >20.2\nu 284 4888 442 >19.9\nw1 4482 4682 197 >19.7\nm2 4276 4476 197 >19.5\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.057 in the direction of the burst\n(Schlegel et al. 1998).\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36184.",
"published": "2024-04-19T16:06:38.628583Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-19T16:06:38.628596Z",
"modified": "2024-04-19T16:06:38.634477Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6696,
"topic": "gcn.circular",
"uuid": "056d1032-e97a-45dc-b5b8-7e78f7a35c81",
"title": "Swift GRB 240419A: Global MASTER-Net observations report",
"submitter": "Hop gcn.circular",
"authors": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"data": {
"date": "24/04/19 17:03:54 GMT",
"from": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36185"
},
"title": "GCN CIRCULAR",
"number": "36185",
"subject": "Swift GRB 240419A: Global MASTER-Net observations report"
},
"message_text": "V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,\nG.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij\n(Lomonosov Moscow State University, SAI, Physics Department),\n\nR. Podesta, C.Lopez, F. Podesta, C.Francile\n(Observatorio Astronomico Felix Aguilar OAFA),\n\nR. Rebolo, M. Serra\n(The Instituto de Astrofisica de Canarias),\n\nD. Buckley\n(South African Astronomical Observatory),\n\nO.A. Gress, N.M. Budnev, O.Ershova\n(Irkutsk State University, API),\n\nL.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,\nA.R.Corella, L.H.Rodriguez\n(INAOE, Guillermo Haro Astrophysics Observatory),\n\nA. Tlatov, D. Dormidontov\n(Kislovodsk Solar Station of the Pulkovo Observatory),\n\nV. Yurkov, A. Gabovich\n(Blagoveschensk Educational State University)\n\nMASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 240419A ( M. H. Siegel et al., GCN 36169) errorbox 54337 sec after notice time and 54397 sec after trigger time at 2024-04-19 16:54:39 UT, with upper limit up to 17.8 mag. Observations started at twilight. The observations began at zenith distance = 25 deg. The sun altitude is -9.6 deg.\n\nThe galactic latitude b = -24 deg., longitude l = 253 deg.\n\n\nReal time updated cover map and OT discovered available here:\nhttps://master.sai.msu.ru/site/master2/observ.php?id$27118\n\nWe obtain a following upper limits.\n\nTmid-T0 | Site |Filt.| Expt. | Limit| Comment\n_________|_____________________|_____|_______|______|________\n\n 54488 | MASTER-SAAO | C | 180 | 17.8 |\nFilter C is a clear (unfiltred) band.\n\n\nThe observation and reduction will continue.\nThe message may be cited.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36185.",
"published": "2024-04-19T17:04:18.403911Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-19T17:04:18.403927Z",
"modified": "2024-04-19T17:04:18.411831Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6697,
"topic": "gcn.circular",
"uuid": "051f252f-f7f9-4a6f-b9bf-bd311a487922",
"title": "GRB 240419B: Enhanced Swift-XRT position",
"submitter": "Hop gcn.circular",
"authors": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"data": {
"date": "24/04/19 17:38:53 GMT",
"from": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36186"
},
"title": "GCN CIRCULAR",
"number": "36186",
"subject": "GRB 240419B: Enhanced Swift-XRT position"
},
"message_text": "J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)\nreport on behalf of the Swift-XRT team.\n\nUsing 1231 s of XRT Photon Counting mode data and 3 UVOT\nimages for GRB 240419B, we find an astrometrically corrected X-ray\nposition (using the XRT-UVOT alignment and matching UVOT field sources\nto the USNO-B1 catalogue): RA, Dec = 325.89679, +4.23479 which is equivalent\nto:\n\nRA (J2000): 21h 43m 35.23s\nDec (J2000): +04d 14' 05.2\"\n\nwith an uncertainty of 2.5 arcsec (radius, 90% confidence).\n\nThis position may be improved as more data are received. The latest\nposition can be viewed at http://www.swift.ac.uk/xrt_positions. Position\nenhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans\net al. (2009, MNRAS, 397, 1177).\n\nThis circular was automatically generated, and is an official product of the\nSwift-XRT team.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36186.",
"published": "2024-04-19T17:39:08.876723Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-19T17:39:08.876739Z",
"modified": "2024-04-19T17:39:08.884904Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6698,
"topic": "gcn.circular",
"uuid": "6021fdb3-0001-4a6a-ade2-5088d84e17c9",
"title": "EP240414A: Terskol Zeiss-2000 optical upper limit",
"submitter": "Hop gcn.circular",
"authors": "Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>",
"data": {
"date": "24/04/19 17:52:39 GMT",
"from": "Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36187"
},
"title": "GCN CIRCULAR",
"number": "36187",
"subject": "EP240414A: Terskol Zeiss-2000 optical upper limit"
},
"message_text": "S. Belkin (IKI), I. Sokolov (INASAN, KIAM), A. Pozanenko (IKI), N. Pankov (HSE) report on behalf of GRB IKI FuN:\n\nWe observed the EP240414A (Lian et al., GCN 36091) with the Zeiss-2000 telescope of Terskol observatory in R-filter on 2024-04-15 starting (UT) 22:55:21. We did not detect the optical counterpart (Aryan et al., GCN 36094; Xu et al., GCN 36105; Jonker et al., GCN 36110; Xiong et al., 36130; Srivastav et al., GCN 36150; Li et al., GCN 36154; Wang et al., GCN 36171;) down to the limiting magnitude of R~22.0. Preliminary photometry of a stacked image is the following\n\nDate UT start t-T0 Exp. Filter OT Err. UL(3sigma)\n (mid, days) (s)\n\n2024-04-15 22:55:21 1.56347 35x90 R n/d n/d 22.0\n\nThe photometry is based on nearby USNO-B1.0 stars.\nUSNO-B1.0\nRA DEC R2\n12:46:00.7214400 -09:43:21.021600 17.15\n12:45:53.8893600 -09:43:46.700400 15.87\n12:46:03.7461600 -09:41:28.521600 15.12\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36187.",
"published": "2024-04-19T17:52:54.430552Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-19T17:52:54.430565Z",
"modified": "2024-04-19T17:52:54.438318Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6747,
"topic": "gcn.circular",
"uuid": "acf6e8cc-566d-4ec2-a798-81d8b1b7a19a",
"title": "GRB 240419B: Swift-XRT refined Analysis",
"submitter": "Hop gcn.circular",
"authors": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"data": {
"date": "24/04/20 08:11:17 GMT",
"from": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36192"
},
"title": "GCN CIRCULAR",
"number": "36192",
"subject": "GRB 240419B: Swift-XRT refined Analysis"
},
"message_text": "J.P. Osborne (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti\n(INAF-OAB), C. Salvaggio (INAF-OAB), J. D. Gropp (PSU), S. Dichiara\n(PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester) and P.A. Evans\nreport on behalf of the Swift-XRT team:\n\nWe have analysed 7.5 ks of XRT data for GRB 240419B, from 141 s to 52.1\nks after the BAT trigger. The data comprise 282 s in Windowed Timing\n(WT) mode (the first 6 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode.\n\nThe late-time light curve (from T0+4.6 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.02 (+0.12, -0.11).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.95 (+/-0.05). The\nbest-fitting absorption column is 1.21 (+0.16, -0.15) x 10^21 cm^-2,\nin excess of the Galactic value of 6.8 x 10^20 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 2.08 (+0.20, -0.19)\nand a best-fitting absorption column of 1.2 (+/-0.5) x 10^21 cm^-2. The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum is 3.2 x 10^-11 (4.2 x 10^-11) erg cm^-2\ncount^-1.\n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t 1.2 (+/-0.5) x 10^21 cm^-2\nGalactic foreground: 6.8 x 10^20 cm^-2\nExcess significance: 1.7 sigma\nPhoton index:\t 2.08 (+0.20, -0.19)\n\nIf the light curve continues to decay with a power-law decay index of\n1.02, the count rate at T+24 hours will be 10.0 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.2 x\n10^-13 (4.2 x 10^-13) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01223072.\n\nThis circular is an official product of the Swift-XRT team.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36192.",
"published": "2024-04-20T08:11:32.401965Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-20T08:11:32.401985Z",
"modified": "2024-04-20T08:11:32.413012Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6748,
"topic": "gcn.circular",
"uuid": "2358342c-fdcf-4a9f-8705-0cc3917053cc",
"title": "GRB 240419A: Swift/UVOT Upper Limits",
"submitter": "Hop gcn.circular",
"authors": "Sam Shilling at Lancaster University <shilling.sam@gmail.com>",
"data": {
"date": "24/04/20 10:46:38 GMT",
"from": "Sam Shilling at Lancaster University <shilling.sam@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36193"
},
"title": "GCN CIRCULAR",
"number": "36193",
"subject": "GRB 240419A: Swift/UVOT Upper Limits"
},
"message_text": "S. P. R. Shilling (Lancaster U.), S. R. Oates (Lancaster U.), A. A. Breeveld (UCL-MSSL), M. De Pasquale (Univ. of Messina) and M. H. Siegel (PSU)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 240419A\n113 s after the BAT trigger (Siegel et al., GCN Circ. 36169).\nNo optical afterglow consistent with the enhanced XRT position (Goad et al., GCN Circ. 36174) is detected in the initial UVOT exposures.\nPreliminary 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first\nfinding chart (FC) exposures and subsequent exposures are:\n\nFilter T_start(s) T_stop(s) Exp(s) Mag\n\nwhite_FC 113 263 147 >20.7\nu_FC 271 521 246 >20.0\nwhite 113 1025 334 >21.3\nv 602 1075 58 >18.6\nb 527 721 39 >19.3\nu 271 869 285 >20.1\nw1 652 845 39 >18.2\nm2 627 1099 58 >18.3\nw2 578 1050 58 >18.6\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.070 in the direction of the burst\n(Schlegel et al. 1998).\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36193.",
"published": "2024-04-20T10:46:56.258657Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-20T10:46:56.258671Z",
"modified": "2024-04-20T10:46:56.266674Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6749,
"topic": "gcn.circular",
"uuid": "dec057a2-cd52-4ff1-b846-105213c88bd7",
"title": "EP240420a: EP-WXT detection of a fast X-ray transient",
"submitter": "Hop gcn.circular",
"authors": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
"data": {
"date": "24/04/20 14:22:52 GMT",
"from": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36194"
},
"title": "GCN CIRCULAR",
"number": "36194",
"subject": "EP240420a: EP-WXT detection of a fast X-ray transient"
},
"message_text": "W. J. Zhang (NAOC, CAS), Y. J. Zhang (THU), S. X. Wen, W. X. Wang, Z. X. Ling, Y. Liu, C. Zhang, C. C. Jin, H. Q. Cheng, W. Chen, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, D. Y. Li, T. Y. Lian, H. Y. Liu, M. J. Liu, Z. Z. Lv, X. Mao, H. W. Pan, X. Pan, H. Sun, Y. L. Wang, Q. Y. Wu, X. P. Xu, Y. F. Xu, H. N. Yang, W. Yuan, M. Zhang, W. D. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Y. Chen, S. M. Jia, S. N. Zhang (IHEP, CAS), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA) on behalf of the Einstein Probe team\n \nSubjects: X-ray, Transient\n \nWe report on the detection of a fast X-ray transient, designated EP240420a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient triggered the WXT on-board processing unit at 2024-04-20T12:04:28 (UTC). The position of the source is R.A. = 228.713 deg, DEC = 14.796 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). The flare lasted for more than 100 seconds and reached a peak flux of ~1 x 10^-8 erg/s/cm^2 in the 0.5-4 keV band. Since only the basic data of the alert was transmitted to the ground, the information on the source property is limited. Further information may be provided once the full scientific telemetry data are received at the EP science center.\n \nNo previously known X-ray sources at a similar flux level are found within 3 arcmin around the source position.  \n \nThe above observation was made with the WXT instrument during the  commissioning phase of EP. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36194.",
"published": "2024-04-20T14:23:07.974294Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-20T14:23:07.974307Z",
"modified": "2024-04-20T14:23:07.982894Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6750,
"topic": "gcn.circular",
"uuid": "b3c23b30-8a91-4b9b-8166-a9cd70a12e3d",
"title": "IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event",
"submitter": "Hop gcn.circular",
"authors": "Giacomo Sommani at Ruhr-Universität Bochum <gsommani@icecube.wisc.edu>",
"data": {
"date": "24/04/20 14:48:26 GMT",
"from": "Giacomo Sommani at Ruhr-Universität Bochum <gsommani@icecube.wisc.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36195"
},
"title": "GCN CIRCULAR",
"number": "36195",
"subject": "IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event"
},
"message_text": "The IceCube Collaboration (http://icecube.wisc.edu/) reports:\n\nOn 2024-04-19 at 23:25:41.05 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Bronze alert stream. The average astrophysical neutrino purity \nfor Bronze alerts is 30%. This alert has an estimated false alarm rate of 3.426 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.\n\nAfter the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/139303_27647445.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:\n\nDate: 2024-04-19\nTime: 23:25:41.05 UT\nRA: 73.17 (+2.60, -3.74 deg 90% PSF containment) J2000\nDec: 1.64 (+1.27, -1.09 deg 90% PSF containment) J2000\n\nWe encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.\n\nOne Fermi-LAT source (listed in the 4FGL-DR4 or 3FHL catalogs) is located within the 90% uncertainty region: 4FGL J0502.6+0036, at RA: 75.65 deg, Dec: 0.61 deg (2.69 deg away from the best-fit event position). \n\nThe IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36195.",
"published": "2024-04-20T14:48:44.279784Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-20T14:48:44.279801Z",
"modified": "2024-04-20T14:48:44.286917Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6753,
"topic": "gcn.circular",
"uuid": "6e895f9e-35c9-4294-a38c-403fa1926a6d",
"title": "GRB 240419B: Swift/UVOT Upper Limits",
"submitter": "Hop gcn.circular",
"authors": "Sam Shilling at Lancaster University <shilling.sam@gmail.com>",
"data": {
"date": "24/04/20 15:20:59 GMT",
"from": "Sam Shilling at Lancaster University <shilling.sam@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36197"
},
"title": "GCN CIRCULAR",
"number": "36197",
"subject": "GRB 240419B: Swift/UVOT Upper Limits"
},
"message_text": "S. P. R. Shilling (Lancaster U.), S. R. Oates (Lancaster U.),\nA. A. Breeveld (UCL-MSSL), N. P. M. Kuin (UCL-MSSL) and S. Dichiara (PSU)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 240419B\n159 s after the BAT trigger (Dichiara et al., GCN Circ. 36180).\nNo optical afterglow consistent with either the enhanced XRT position\n(Osborne et al., GCN Circ. 36186) or the NOT optical afterglow position\n(Malesani et al., GCN Circ. 36191) is detected in the initial UVOT exposures.\nPreliminary 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first\nfinding chart (FC) exposures and subsequent exposures are:\n\nFilter T_start(s) T_stop(s) Exp(s) Mag\n\nwhite_FC 159 308 147 >20.3\nu_FC 317 567 246 >19.5\nwhite 159 790 186 >20.4\nv 647 667 19 >17.3\nb 572 765 39 >18.6\nu 317 741 265 >19.5\nw1 696 716 19 >17.5\nm2 672 691 19 >17.2\nw2 623 643 19 >17.6\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.077 in the direction of the burst\n(Schlegel et al. 1998).\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36197.",
"published": "2024-04-20T15:21:15.378488Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-20T15:21:15.378506Z",
"modified": "2024-04-20T15:21:15.388855Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6756,
"topic": "gcn.circular",
"uuid": "6e924f4e-f5a3-44a3-b529-e7d7e69df847",
"title": "IceCube Alert 240419.98: Global MASTER-Net observations report",
"submitter": "Hop gcn.circular",
"authors": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"data": {
"date": "24/04/20 18:39:50 GMT",
"from": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36198"
},
"title": "GCN CIRCULAR",
"number": "36198",
"subject": "IceCube Alert 240419.98: Global MASTER-Net observations report"
},
"message_text": "V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,\nG.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij\n(Lomonosov Moscow State University, SAI, Physics Department),\n\nR. Podesta, C.Lopez, F. Podesta, C.Francile\n(Observatorio Astronomico Felix Aguilar OAFA),\n\nR. Rebolo, M. Serra\n(The Instituto de Astrofisica de Canarias),\n\nD. Buckley\n(South African Astronomical Observatory),\n\nO.A. Gress, N.M. Budnev, O.Ershova\n(Irkutsk State University, API),\n\nL.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,\nA.R.Corella, L.H.Rodriguez\n(INAOE, Guillermo Haro Astrophysics Observatory),\n\nA. Tlatov, D. Dormidontov\n(Kislovodsk Solar Station of the Pulkovo Observatory),\n\nV. Yurkov, A. Gabovich\n(Blagoveschensk Educational State University)\n\nMASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the IceCube Alert 240419.98 (trigger No 27647445,04h 56m 36.72s , +01d 04m 48.0s, R=0.93) errorbox 62953 sec after notice time and 63005 sec after trigger time at 2024-04-20 16:55:46 UT, with upper limit up to 17.8 mag. Observations started at twilight. The observations began at zenith distance = 59 deg. The sun altitude is -10.0 deg.\n\nMASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the IceCube Alert 240419.98 errorbox 63247 sec after notice time and 63298 sec after trigger time at 2024-04-20 17:00:39 UT, with upper limit up to 14.6 mag. Observations started at twilight. The observations began at zenith distance = 77 deg. The sun altitude is -11.3 deg.\n\nThe galactic latitude b = -24 deg., longitude l = 198 deg.\n\n\nReal time updated cover map and OT discovered available here:\nhttps://master.sai.msu.ru/site/master2/observ.php?id$28145\n\nWe obtain a following upper limits.\n\nTmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment\n_________|_____________________|_____________________|____________________________________|_____|_______|_______|________\n\n 63036 | 2024-04-20 16:55:46 | MASTER-SAAO | (04h 46m 18.98s , +01d 16m 48.1s) | C | 60 | 16.5 |\n 63036 | 2024-04-20 16:55:46 | MASTER-SAAO | (04h 48m 02.63s , +01d 04m 23.4s) | C | 60 | 16.0 |\n 63389 | 2024-04-20 17:00:39 | MASTER-Kislovodsk | (04h 49m 31.32s , +01d 55m 29.2s) | C | 180 | 12.4 |\n 64055 | 2024-04-20 17:12:46 | MASTER-SAAO | (04h 48m 01.33s , +01d 04m 01.3s) | C | 60 | 16.1 |\n 64561 | 2024-04-20 17:21:11 | MASTER-SAAO | (04h 48m 31.66s , +02d 57m 38.3s) | C | 60 | 17.6 |\n 64940 | 2024-04-20 17:27:30 | MASTER-Kislovodsk | (05h 04m 41.95s , +01d 08m 28.7s) | C | 60 | 14.3 |\n 64940 | 2024-04-20 17:27:30 | MASTER-Kislovodsk | (05h 01m 00.38s , +01d 29m 17.0s) | C | 60 | 14.6 |\n 65020 | 2024-04-20 17:28:50 | MASTER-Kislovodsk | (05h 01m 16.88s , +03d 24m 39.7s) | C | 60 | 14.1 |\n 65020 | 2024-04-20 17:28:50 | MASTER-Kislovodsk | (05h 04m 59.16s , +03d 03m 48.3s) | C | 60 | 13.9 |\n 65096 | 2024-04-20 17:30:06 | MASTER-SAAO | (04h 48m 11.29s , +01d 05m 32.6s) | C | 60 | 17.8 |\n 65639 | 2024-04-20 17:39:10 | MASTER-SAAO | (04h 48m 38.09s , +02d 59m 01.1s) | C | 60 | 16.4 |\n 65732 | 2024-04-20 17:40:42 | MASTER-SAAO | (05h 03m 11.15s , -00d 49m 58.1s) | C | 60 | 16.9 |\n 65824 | 2024-04-20 17:42:14 | MASTER-SAAO | (04h 48m 11.49s , -00d 49m 49.2s) | C | 60 | 17.0 |\n 66581 | 2024-04-20 17:53:51 | MASTER-SAAO | (04h 52m 10.45s , +01d 32m 00.0s) | C | 180 | 15.7 |\n 66734 | 2024-04-20 17:57:25 | MASTER-SAAO | (05h 03m 17.66s , -00d 49m 18.7s) | C | 60 | 17.0 |\n 66826 | 2024-04-20 17:58:57 | MASTER-SAAO | (04h 48m 19.58s , -00d 49m 09.1s) | C | 60 | 17.1 |\n 67589 | 2024-04-20 18:10:40 | MASTER-SAAO | (04h 52m 21.99s , +01d 32m 36.8s) | C | 180 | 15.3 |\n 67742 | 2024-04-20 18:14:13 | MASTER-SAAO | (05h 03m 25.14s , -00d 48m 42.1s) | C | 60 | 16.8 |\n 67835 | 2024-04-20 18:15:45 | MASTER-SAAO | (04h 48m 33.70s , -00d 48m 23.9s) | C | 60 | 17.0 |\nFilter C is a clear (unfiltred) band.\n\n\nThe observation and reduction will continue.\nThe message may be cited.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36198.",
"published": "2024-04-20T18:40:08.690494Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-20T18:40:08.690509Z",
"modified": "2024-04-20T18:40:08.699600Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6759,
"topic": "gcn.circular",
"uuid": "4e8915f4-4848-49d6-96e2-10fe7063240a",
"title": "GRB240418A - Candidate afterglow from NIRES",
"submitter": "Hop gcn.circular",
"authors": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"data": {
"date": "24/04/20 19:35:35 GMT",
"from": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36199"
},
"title": "GCN CIRCULAR",
"number": "36199",
"subject": "GRB240418A - Candidate afterglow from NIRES"
},
"message_text": "Viraj Karambelkar (Caltech), Kaew Tinyanont (NARIT), Sam Rose (Caltech),\nTomas Ahumada (Caltech), Robert Stein (Caltech), Nathan Lourie (MIT),\nDanielle Frostig (MIT), Geoffrey Mo (MIT), Robert Simcoe (MIT), Mansi\nKasliwal (Caltech)\n\nWe observed the field of the long GRB 240418A (GCN 36162; GCN 36166; GCN\n36177; GCN 36184) in the near-infrared K-prime band with the NIRES\nacquisition camera on the Keck II telescope starting at UTC\n2024-04-19T09:56:00 (~14 hours since trigger). The observations lasted for\n300 sec. (25 sec, 12 coadds).\n\nWe find an uncataloged source at RA = 239.3744, Dec = 23.5961 that is 3.1\narcsec from the centroid of the GRB position and within its 3.6 arcsec\nlocalization (from GCN 36166). This source has m_Kp ~ 20.9 +/- 0.1 mag\n(AB). There is no source at this location in an archival Ks-band image from\nthe UKIRT hemisphere survey (Lucas et al. 2008), and a deep optical image\nfrom the Legacy Survey. However, we note that our NIRES observations are\nmore sensitive than the archival UKIRT observations, so it is possible that\nthe NIRES source is an unrelated background source.\n\nWe also observed this source in the J-band with the WINTER camera on the\nPalomar 40-inch telescope (Lourie et al. 2021) on 2024-04-19T09:00:14 and\ndid not detect it to a limiting magnitude of m_J ~ 19 mag.\n\nFurther observations are encouraged.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36199.",
"published": "2024-04-20T19:35:48.437651Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-20T19:35:48.437670Z",
"modified": "2024-04-20T19:35:48.444664Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6764,
"topic": "gcn.circular",
"uuid": "f0877af9-9634-4fe8-9b6c-3f08b9c4488f",
"title": "GRB240419A: Skynet Optical Afterglow Analysis",
"submitter": "Hop gcn.circular",
"authors": "maedubay@unc.edu",
"data": {
"date": "24/04/20 21:12:37 GMT",
"from": "maedubay@unc.edu",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36200"
},
"title": "GCN CIRCULAR",
"number": "36200",
"subject": "GRB240419A: Skynet Optical Afterglow Analysis"
},
"message_text": "Megan Dubay, Donovan Schlekat, Dylan Dutton, Daniel Reichart, Joshua Haislip, and Vladimir Kouprianov report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill.\n\nWe observed the field of GRB 240419A with one of Skynetâs 16â-diameter PROMPT telescopes at CTIO. The first detection occurred in the I band approximately 1 hour after the trigger reported by Swift (Siegel et al., GCN 36169).\n\nWe detect the afterglow with coordinates consistent with those reported by VLT (B. Schneider et al., GCN 36175) and REM (Ferro et al., GCN 36183).\n\nThe coordinates are:\t\nR.A. (J2000): 06:18:08.18\nDec. (J2000): -44:59:57.60\n\nWe report the photometry below.\n\nExpLen | Filter | Mag | Mag Error | MJD (Center) \n------------------------------------------------\n45x8 | I | 19.06 | 0.199 | 60419.119\n60x8 | R | ----- | ----- | 60419.119\n\nWe report non-detection in the R-band from the reported time with an upper magnitude limit of 20.39.\n \nWe note that the large R-I color is consistent with the presence of the Lyman-alpha forest in the R band, given its large redshift (Schneider et al., GCN 36176, Lamb & Reichart 2000).\n\nOur images have been calibrated using stars from the APASS catalog.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36200.",
"published": "2024-04-20T21:12:52.496511Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-20T21:12:52.496525Z",
"modified": "2024-04-20T21:12:52.502290Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6765,
"topic": "gcn.circular",
"uuid": "e7fe2728-7f35-4dd9-93c1-38407abfb1ec",
"title": "Fermi trigger No 735280430: Global MASTER-Net observations report",
"submitter": "Hop gcn.circular",
"authors": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"data": {
"date": "24/04/20 23:30:46 GMT",
"from": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36201"
},
"title": "GCN CIRCULAR",
"number": "36201",
"subject": "Fermi trigger No 735280430: Global MASTER-Net observations report"
},
"message_text": "V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,\nG.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij\n(Lomonosov Moscow State University, SAI, Physics Department),\n\nR. Podesta, C.Lopez, F. Podesta, C.Francile\n(Observatorio Astronomico Felix Aguilar OAFA),\n\nR. Rebolo, M. Serra\n(The Instituto de Astrofisica de Canarias),\n\nD. Buckley\n(South African Astronomical Observatory),\n\nO.A. Gress, N.M. Budnev, O.Ershova\n(Irkutsk State University, API),\n\nL.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,\nA.R.Corella, L.H.Rodriguez\n(INAOE, Guillermo Haro Astrophysics Observatory),\n\nA. Tlatov, D. Dormidontov\n(Kislovodsk Solar Station of the Pulkovo Observatory),\n\nV. Yurkov, A. Gabovich\n(Blagoveschensk Educational State University)\n\nMASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB240420.19 (trigger No 735280430,17h 04m 21.60s , -27d 01m 12.0s, R=5.66) errorbox 61985 sec after notice time and 62023 sec after trigger time at 2024-04-20 21:47:28 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 71 deg. The sun altitude is -34.5 deg.\n\nMASTER-Tavrida robotic telescope located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB240420.19 errorbox 66581 sec after notice time and 66619 sec after trigger time at 2024-04-20 23:04:05 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 76 deg. The sun altitude is -31.1 deg.\n\nThe galactic latitude b = 8 deg., longitude l = 357 deg.\n\n\nReal time updated cover map and OT discovered available here:\nhttps://master.sai.msu.ru/site/master2/observ.php?id$28865\n\nWe obtain a following upper limits.\n\nTmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment\n_________|_____________________|_____________________|____________________________________|_____|_______|_______|________\n\n 62053 | 2024-04-20 21:47:28 | MASTER-Kislovodsk | (16h 40m 07.62s , -21d 44m 13.2s) | C | 60 | 15.7 |\n 62312 | 2024-04-20 21:51:47 | MASTER-Kislovodsk | (17h 00m 01.31s , -19d 53m 35.1s) | C | 60 | 14.9 |\n 62392 | 2024-04-20 21:53:07 | MASTER-Kislovodsk | (16h 37m 32.02s , -23d 40m 27.0s) | C | 60 | 16.5 |\n 62713 | 2024-04-20 21:58:28 | MASTER-Kislovodsk | (17h 04m 36.11s , -27d 05m 19.3s) | C | 60 | 14.9 |\n 62713 | 2024-04-20 21:58:28 | MASTER-Kislovodsk | (17h 09m 14.20s , -27d 28m 52.4s) | C | 60 | 14.0 |\n 62793 | 2024-04-20 21:59:48 | MASTER-Kislovodsk | (17h 04m 45.21s , -25d 10m 19.0s) | C | 60 | 14.9 |\n 62793 | 2024-04-20 21:59:48 | MASTER-Kislovodsk | (17h 09m 19.54s , -25d 33m 50.2s) | C | 60 | 14.9 |\n 62954 | 2024-04-20 22:02:29 | MASTER-Kislovodsk | (16h 40m 10.91s , -21d 47m 06.9s) | C | 60 | 16.6 |\n 63034 | 2024-04-20 22:03:49 | MASTER-Kislovodsk | (16h 48m 02.61s , -25d 11m 29.9s) | C | 60 | 15.9 |\n 63034 | 2024-04-20 22:03:49 | MASTER-Kislovodsk | (16h 52m 37.94s , -25d 34m 56.5s) | C | 60 | 16.2 |\n 63194 | 2024-04-20 22:06:29 | MASTER-Kislovodsk | (16h 47m 34.30s , -27d 05m 48.8s) | C | 60 | 16.4 |\n 63194 | 2024-04-20 22:06:29 | MASTER-Kislovodsk | (16h 52m 13.47s , -27d 29m 17.8s) | C | 60 | 16.1 |\n 63275 | 2024-04-20 22:07:50 | MASTER-Kislovodsk | (17h 00m 09.04s , -19d 51m 27.0s) | C | 60 | 16.7 |\n 63355 | 2024-04-20 22:09:10 | MASTER-Kislovodsk | (16h 37m 26.69s , -23d 40m 00.0s) | C | 60 | 17.0 |\n 63676 | 2024-04-20 22:14:31 | MASTER-Kislovodsk | (17h 04m 42.49s , -27d 05m 55.2s) | C | 60 | 14.6 |\n 63676 | 2024-04-20 22:14:31 | MASTER-Kislovodsk | (17h 09m 21.17s , -27d 29m 27.5s) | C | 60 | 14.1 |\n 63756 | 2024-04-20 22:15:51 | MASTER-Kislovodsk | (17h 04m 49.41s , -25d 10m 05.4s) | C | 60 | 15.2 |\n 63756 | 2024-04-20 22:15:51 | MASTER-Kislovodsk | (17h 09m 24.18s , -25d 33m 36.3s) | C | 60 | 15.1 |\n 63837 | 2024-04-20 22:17:12 | MASTER-Kislovodsk | (17h 05m 39.92s , -28d 59m 31.4s) | C | 60 | 14.5 |\n 63837 | 2024-04-20 22:17:12 | MASTER-Kislovodsk | (17h 10m 22.70s , -29d 23m 12.8s) | C | 60 | 14.6 |\n 63917 | 2024-04-20 22:18:33 | MASTER-Kislovodsk | (17h 06m 07.40s , -23d 16m 30.2s) | C | 60 | 15.3 |\n 63917 | 2024-04-20 22:18:33 | MASTER-Kislovodsk | (17h 10m 38.64s , -23d 40m 02.1s) | C | 60 | 14.2 |\n 63998 | 2024-04-20 22:19:53 | MASTER-Kislovodsk | (16h 47m 57.54s , -25d 10m 40.4s) | C | 60 | 15.8 |\n 63998 | 2024-04-20 22:19:53 | MASTER-Kislovodsk | (16h 52m 32.97s , -25d 34m 13.6s) | C | 60 | 16.0 |\n 64078 | 2024-04-20 22:21:13 | MASTER-Kislovodsk | (16h 48m 13.19s , -28d 57m 35.4s) | C | 60 | 15.5 |\n 64078 | 2024-04-20 22:21:13 | MASTER-Kislovodsk | (16h 52m 56.51s , -29d 21m 16.0s) | C | 60 | 15.3 |\n 64158 | 2024-04-20 22:22:33 | MASTER-Kislovodsk | (16h 47m 39.00s , -27d 04m 37.5s) | C | 60 | 16.2 |\n 64158 | 2024-04-20 22:22:33 | MASTER-Kislovodsk | (16h 52m 18.11s , -27d 28m 15.8s) | C | 60 | 15.8 |\n 64248 | 2024-04-20 22:24:03 | MASTER-Kislovodsk | (16h 49m 29.07s , -23d 17m 40.8s) | C | 60 | 16.8 |\n 64328 | 2024-04-20 22:25:23 | MASTER-Kislovodsk | (17h 21m 48.26s , -27d 06m 09.2s) | C | 60 | 15.9 |\n 64328 | 2024-04-20 22:25:23 | MASTER-Kislovodsk | (17h 26m 26.05s , -27d 29m 49.4s) | C | 60 | 15.0 |\n 64408 | 2024-04-20 22:26:43 | MASTER-Kislovodsk | (17h 21m 38.17s , -25d 10m 18.6s) | C | 60 | 15.0 |\n 64408 | 2024-04-20 22:26:43 | MASTER-Kislovodsk | (17h 26m 12.26s , -25d 33m 53.5s) | C | 60 | 14.6 |\n 64489 | 2024-04-20 22:28:04 | MASTER-Kislovodsk | (17h 08m 25.36s , -21d 23m 35.4s) | C | 60 | 16.4 |\n 64489 | 2024-04-20 22:28:04 | MASTER-Kislovodsk | (17h 12m 53.96s , -21d 47m 01.9s) | C | 60 | 16.3 |\n 64569 | 2024-04-20 22:29:24 | MASTER-Kislovodsk | (17h 07m 55.27s , -30d 52m 01.9s) | C | 60 | 13.7 |\n 64569 | 2024-04-20 22:29:24 | MASTER-Kislovodsk | (17h 12m 42.91s , -31d 15m 47.1s) | C | 60 | 13.4 |\n 64649 | 2024-04-20 22:30:44 | MASTER-Kislovodsk | (17h 04m 39.25s , -27d 04m 46.4s) | C | 60 | 16.1 |\n 64649 | 2024-04-20 22:30:44 | MASTER-Kislovodsk | (17h 09m 18.16s , -27d 28m 22.3s) | C | 60 | 15.7 |\n 64730 | 2024-04-20 22:32:05 | MASTER-Kislovodsk | (17h 04m 48.13s , -25d 09m 44.8s) | C | 60 | 16.3 |\n 64730 | 2024-04-20 22:32:05 | MASTER-Kislovodsk | (17h 09m 23.29s , -25d 33m 17.8s) | C | 60 | 16.0 |\n 64810 | 2024-04-20 22:33:25 | MASTER-Kislovodsk | (17h 05m 43.94s , -28d 58m 40.3s) | C | 60 | 15.4 |\n 64810 | 2024-04-20 22:33:25 | MASTER-Kislovodsk | (17h 10m 27.15s , -29d 22m 20.2s) | C | 60 | 14.9 |\n 64907 | 2024-04-20 22:35:02 | MASTER-Kislovodsk | (17h 06m 02.73s , -23d 17m 45.1s) | C | 60 | 16.6 |\n 64907 | 2024-04-20 22:35:02 | MASTER-Kislovodsk | (17h 10m 34.73s , -23d 41m 17.5s) | C | 60 | 16.3 |\n 64987 | 2024-04-20 22:36:23 | MASTER-Kislovodsk | (16h 48m 04.71s , -25d 10m 59.4s) | C | 60 | 16.0 |\n 64987 | 2024-04-20 22:36:23 | MASTER-Kislovodsk | (16h 52m 40.79s , -25d 34m 32.1s) | C | 60 | 16.2 |\n 65067 | 2024-04-20 22:37:42 | MASTER-Kislovodsk | (16h 48m 18.82s , -28d 57m 47.2s) | C | 60 | 16.3 |\n 65067 | 2024-04-20 22:37:43 | MASTER-Kislovodsk | (16h 53m 02.83s , -29d 21m 25.9s) | C | 60 | 16.1 |\n 65148 | 2024-04-20 22:39:03 | MASTER-Kislovodsk | (16h 47m 37.72s , -27d 05m 13.0s) | C | 60 | 16.6 |\n 65148 | 2024-04-20 22:39:03 | MASTER-Kislovodsk | (16h 52m 17.55s , -27d 28m 48.7s) | C | 60 | 16.4 |\n 65228 | 2024-04-20 22:40:23 | MASTER-Kislovodsk | (16h 49m 35.53s , -23d 15m 48.5s) | C | 60 | 16.3 |\n 65228 | 2024-04-20 22:40:23 | MASTER-Kislovodsk | (16h 54m 08.19s , -23d 39m 19.4s) | C | 60 | 16.4 |\n 65308 | 2024-04-20 22:41:43 | MASTER-Kislovodsk | (17h 21m 44.02s , -27d 04m 53.5s) | C | 60 | 16.2 |\n 65308 | 2024-04-20 22:41:43 | MASTER-Kislovodsk | (17h 26m 22.47s , -27d 28m 35.8s) | C | 60 | 15.4 |\n 65388 | 2024-04-20 22:43:04 | MASTER-Kislovodsk | (17h 26m 11.48s , -25d 33m 32.4s) | C | 60 | 15.7 |\n 65388 | 2024-04-20 22:43:04 | MASTER-Kislovodsk | (17h 21m 36.86s , -25d 09m 52.9s) | C | 60 | 16.4 |\n 65468 | 2024-04-20 22:44:24 | MASTER-Kislovodsk | (17h 08m 29.66s , -21d 22m 42.4s) | C | 60 | 16.9 |\n 65468 | 2024-04-20 22:44:24 | MASTER-Kislovodsk | (17h 12m 58.56s , -21d 46m 14.4s) | C | 60 | 16.7 |\n 65549 | 2024-04-20 22:45:44 | MASTER-Kislovodsk | (17h 07m 51.05s , -30d 53m 30.8s) | C | 60 | 15.2 |\n 65549 | 2024-04-20 22:45:44 | MASTER-Kislovodsk | (17h 12m 38.86s , -31d 17m 18.5s) | C | 60 | 14.7 |\n 65629 | 2024-04-20 22:47:04 | MASTER-Kislovodsk | (17h 23m 08.51s , -28d 59m 31.1s) | C | 60 | 15.8 |\n 65629 | 2024-04-20 22:47:04 | MASTER-Kislovodsk | (17h 27m 51.06s , -29d 23m 17.3s) | C | 60 | 14.8 |\n 65709 | 2024-04-20 22:48:24 | MASTER-Kislovodsk | (16h 50m 11.39s , -30d 51m 41.9s) | C | 60 | 16.1 |\n 65709 | 2024-04-20 22:48:24 | MASTER-Kislovodsk | (16h 54m 59.72s , -31d 15m 25.0s) | C | 60 | 16.0 |\n 65790 | 2024-04-20 22:49:45 | MASTER-Kislovodsk | (17h 22m 40.78s , -23d 17m 22.0s) | C | 60 | 16.7 |\n 65790 | 2024-04-20 22:49:45 | MASTER-Kislovodsk | (17h 27m 12.13s , -23d 40m 56.8s) | C | 60 | 16.1 |\n 65870 | 2024-04-20 22:51:05 | MASTER-Kislovodsk | (17h 06m 11.42s , -23d 15m 38.2s) | C | 60 | 16.6 |\n 65870 | 2024-04-20 22:51:05 | MASTER-Kislovodsk | (17h 10m 43.51s , -23d 39m 09.8s) | C | 60 | 16.4 |\n 65950 | 2024-04-20 22:52:25 | MASTER-Kislovodsk | (16h 52m 03.72s , -21d 22m 21.8s) | C | 60 | 16.7 |\n 65950 | 2024-04-20 22:52:25 | MASTER-Kislovodsk | (16h 56m 33.50s , -21d 45m 46.6s) | C | 60 | 16.8 |\n 66030 | 2024-04-20 22:53:45 | MASTER-Kislovodsk | (16h 48m 16.83s , -28d 57m 12.8s) | C | 60 | 16.3 |\n 66030 | 2024-04-20 22:53:45 | MASTER-Kislovodsk | (16h 53m 00.94s , -29d 20m 45.7s) | C | 60 | 16.1 |\n 66191 | 2024-04-20 22:56:26 | MASTER-Kislovodsk | (16h 49m 33.03s , -23d 17m 16.2s) | C | 60 | 15.9 |\n 66191 | 2024-04-20 22:56:26 | MASTER-Kislovodsk | (16h 54m 06.16s , -23d 40m 38.8s) | C | 60 | 15.2 |\n 66271 | 2024-04-20 22:57:46 | MASTER-Kislovodsk | (17h 21m 52.43s , -27d 05m 30.3s) | C | 60 | 16.4 |\n 66271 | 2024-04-20 22:57:46 | MASTER-Kislovodsk | (17h 26m 31.49s , -27d 29m 00.9s) | C | 60 | 15.5 |\n 66351 | 2024-04-20 22:59:06 | MASTER-Kislovodsk | (17h 21m 41.12s , -25d 10m 08.9s) | C | 60 | 16.6 |\n 66351 | 2024-04-20 22:59:06 | MASTER-Kislovodsk | (17h 26m 16.48s , -25d 33m 36.4s) | C | 60 | 15.8 |\n 66432 | 2024-04-20 23:00:27 | MASTER-Kislovodsk | (17h 08m 28.01s , -21d 23m 11.6s) | C | 60 | 16.2 |\n 66432 | 2024-04-20 23:00:27 | MASTER-Kislovodsk | (17h 12m 57.68s , -21d 46m 31.2s) | C | 60 | 16.8 |\n 66512 | 2024-04-20 23:01:47 | MASTER-Kislovodsk | (17h 07m 57.89s , -30d 51m 38.5s) | C | 60 | 15.5 |\n 66512 | 2024-04-20 23:01:47 | MASTER-Kislovodsk | (17h 12m 46.44s , -31d 15m 12.4s) | C | 60 | 15.3 |\n 66592 | 2024-04-20 23:03:07 | MASTER-Kislovodsk | (17h 23m 05.00s , -28d 58m 34.0s) | C | 60 | 16.2 |\n 66592 | 2024-04-20 23:03:07 | MASTER-Kislovodsk | (17h 27m 48.36s , -29d 22m 07.2s) | C | 60 | 15.4 |\n 66650 | 2024-04-20 23:04:05 | MASTER-Tavrida | (17h 01m 59.14s , -27d 41m 47.1s) | C | 60 | 15.0 |\n 66672 | 2024-04-20 23:04:27 | MASTER-Kislovodsk | (16h 50m 09.25s , -30d 51m 07.7s) | C | 60 | 16.2 |\n 66672 | 2024-04-20 23:04:27 | MASTER-Kislovodsk | (16h 54m 58.22s , -31d 14m 37.1s) | C | 60 | 16.1 |\n 66724 | 2024-04-20 23:05:19 | MASTER-Tavrida | (17h 02m 07.96s , -25d 46m 53.5s) | C | 60 | 15.6 |\n 66752 | 2024-04-20 23:05:47 | MASTER-Kislovodsk | (17h 22m 45.21s , -23d 16m 40.2s) | C | 60 | 16.8 |\n 66752 | 2024-04-20 23:05:47 | MASTER-Kislovodsk | (17h 27m 17.31s , -23d 40m 02.9s) | C | 60 | 16.4 |\n 66799 | 2024-04-20 23:06:34 | MASTER-Tavrida | (17h 02m 58.57s , -29d 35m 02.5s) | C | 60 | 12.8 |\n 66832 | 2024-04-20 23:07:07 | MASTER-Kislovodsk | (17h 24m 45.16s , -21d 23m 42.5s) | C | 60 | 17.0 |\n 66873 | 2024-04-20 23:07:48 | MASTER-Tavrida | (16h 45m 24.07s , -25d 47m 14.7s) | C | 60 | 16.4 |\n 66913 | 2024-04-20 23:08:28 | MASTER-Kislovodsk | (16h 52m 11.90s , -21d 23m 07.0s) | C | 60 | 16.8 |\n 66913 | 2024-04-20 23:08:28 | MASTER-Kislovodsk | (16h 56m 41.99s , -21d 46m 23.5s) | C | 60 | 16.9 |\n 66947 | 2024-04-20 23:09:02 | MASTER-Tavrida | (16h 44m 52.00s , -27d 41m 25.4s) | C | 60 | 16.4 |\n 66993 | 2024-04-20 23:09:48 | MASTER-Kislovodsk | (17h 25m 40.07s , -30d 52m 01.3s) | C | 60 | 16.1 |\n 66993 | 2024-04-20 23:09:48 | MASTER-Kislovodsk | (17h 30m 27.79s , -31d 15m 37.3s) | C | 60 | 15.8 |\n 67022 | 2024-04-20 23:10:17 | MASTER-Tavrida | (16h 53m 02.31s , -20d 04m 44.0s) | C | 60 | 16.8 |\n 67073 | 2024-04-20 23:11:08 | MASTER-Kislovodsk | (17h 16m 18.51s , -19d 52m 24.8s) | C | 60 | 16.9 |\n 67153 | 2024-04-20 23:12:28 | MASTER-Kislovodsk | (17h 11m 25.84s , -32d 45m 24.4s) | C | 60 | 14.0 |\n 67153 | 2024-04-20 23:12:28 | MASTER-Kislovodsk | (17h 16m 19.21s , -33d 09m 04.1s) | C | 60 | 14.5 |\n 67233 | 2024-04-20 23:13:48 | MASTER-Kislovodsk | (16h 53m 15.37s , -32d 46m 02.9s) | C | 60 | 15.4 |\n 67233 | 2024-04-20 23:13:48 | MASTER-Kislovodsk | (16h 58m 09.13s , -33d 09m 40.2s) | C | 60 | 14.7 |\n 67542 | 2024-04-20 23:18:58 | MASTER-Tavrida | (17h 03m 27.27s , -23d 53m 52.6s) | C | 60 | 15.9 |\n 67554 | 2024-04-20 23:19:09 | MASTER-Kislovodsk | (17h 23m 13.00s , -28d 59m 09.4s) | C | 60 | 16.3 |\n 67554 | 2024-04-20 23:19:09 | MASTER-Kislovodsk | (17h 27m 56.21s , -29d 22m 46.0s) | C | 60 | 15.4 |\n 67616 | 2024-04-20 23:20:11 | MASTER-Tavrida | (17h 02m 00.90s , -27d 40m 42.1s) | C | 60 | 16.0 |\n 67634 | 2024-04-20 23:20:29 | MASTER-Kislovodsk | (16h 50m 15.36s , -30d 51m 25.5s) | C | 60 | 16.2 |\n 67634 | 2024-04-20 23:20:29 | MASTER-Kislovodsk | (16h 55m 04.10s , -31d 14m 59.7s) | C | 60 | 16.1 |\n 67689 | 2024-04-20 23:21:24 | MASTER-Tavrida | (17h 10m 55.81s , -27d 41m 28.6s) | C | 60 | 15.2 |\n 67714 | 2024-04-20 23:21:50 | MASTER-Kislovodsk | (17h 22m 43.44s , -23d 17m 05.8s) | C | 60 | 16.7 |\n 67714 | 2024-04-20 23:21:50 | MASTER-Kislovodsk | (17h 27m 15.66s , -23d 40m 31.3s) | C | 60 | 16.2 |\n 67761 | 2024-04-20 23:22:36 | MASTER-Tavrida | (17h 02m 06.52s , -25d 46m 16.4s) | C | 60 | 16.2 |\n 67795 | 2024-04-20 23:23:10 | MASTER-Kislovodsk | (17h 24m 52.61s , -21d 21m 41.2s) | C | 60 | 17.1 |\n 67835 | 2024-04-20 23:23:50 | MASTER-Tavrida | (17h 11m 05.33s , -25d 47m 27.4s) | C | 60 | 16.3 |\n 67875 | 2024-04-20 23:24:30 | MASTER-Kislovodsk | (16h 52m 07.24s , -21d 22m 05.5s) | C | 60 | 16.9 |\n 67875 | 2024-04-20 23:24:30 | MASTER-Kislovodsk | (16h 56m 37.70s , -21d 45m 22.8s) | C | 60 | 16.9 |\n 67955 | 2024-04-20 23:25:50 | MASTER-Kislovodsk | (17h 30m 26.95s , -31d 14m 49.5s) | C | 60 | 15.9 |\nFilter C is a clear (unfiltred) band.\n\n\nThe observation and reduction will continue.\nThe message may be cited.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36201.",
"published": "2024-04-20T23:31:00.094751Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-20T23:31:00.094776Z",
"modified": "2024-04-20T23:31:00.145434Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6785,
"topic": "gcn.circular",
"uuid": "ecff41ff-24ba-4a4a-8761-fb4aa638dc63",
"title": "EP240420a: Nanshan optical counterpart observations",
"submitter": "Hop gcn.circular",
"authors": "Dong Xu at NAOC/CAS <dxu@nao.cas.cn>",
"data": {
"date": "24/04/21 09:48:59 GMT",
"from": "Dong Xu at NAOC/CAS <dxu@nao.cas.cn>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36207"
},
"title": "GCN CIRCULAR",
"number": "36207",
"subject": "EP240420a: Nanshan optical counterpart observations"
},
"message_text": "U. Mahmut, A. Iskandar, J.Z. Liu, Y. Zhang (XAO), J. An, Z.P. Zhu, X. Liu, S.Q. Jiang, S.Y. Fu, D. Xu (NAOC) report on behalf of a large collaboration:\n\nWe observed the field of the X-ray transient, EP 240420a, detected by EP/WXT (Zhang et al., GCN 36194) using the 1-m Nanshan Optical Wide-field Telescope (NOWT) and the Half-Meter-Telescope (HMT) located at Nanshan, Xinjiang, China.\n\nAt series of 300 s and 200 s NOWT frames in the V-band were obtained starting at 16:00:05 UT on 2024-04-20 and the median time is 4.58 hr after the EP trigger. An optical transient (OT) is marginally detected at the counterpart candidate position reported by NOT (An et al., GCN 36202) with V ~ 21.8 mag, calibrated with the PanSTAR field.\n\nAt HMT 40 x 60 frames without any filter were obtained and the median time is 4.32 hr after the EP trigger. No credible source is detected at the NOT position, down to a 3-sigma limiting magnitude of r ~ 20.0, calibrated with the PanSTAR field.\n\nThe NOT candidate is within the EP/FXT error circle (Han et al., GCN 36203). Comparison of the Nanshan observation with the NOT observation shows that the OT is decaying, being consistent with the behavior of GRB optical afterglows.\n\nWe therefore think the OT is the optical counterpart of EP 240420a, which could be a GRB.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36207.",
"published": "2024-04-21T09:49:19.694084Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-21T09:49:19.694111Z",
"modified": "2024-04-21T09:49:19.702273Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6786,
"topic": "gcn.circular",
"uuid": "6765c541-1ab9-410d-91d1-47d9091889f3",
"title": "GRB 240421B: Swift detection of a burst",
"submitter": "Hop gcn.circular",
"authors": "Simone Dichiara at Pennsylvania State University <sbd5667@psu.edu>",
"data": {
"date": "24/04/21 10:02:18 GMT",
"from": "Simone Dichiara at Pennsylvania State University <sbd5667@psu.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36208"
},
"title": "GCN CIRCULAR",
"number": "36208",
"subject": "GRB 240421B: Swift detection of a burst"
},
"message_text": "\nM. A. Williams (PSU), J. J. DeLaunay (PSU), S. Dichiara (PSU),\nJ.D. Gropp (PSU) and T. Sakamoto (AGU) report on behalf of the Neil\nGehrels Swift Observatory Team:\n\nAt 09:42:54 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 240421B (trigger\u001223470). Swift slewed immediately to the burst.\nThe BAT on-board calculated location is\nRA, Dec 299.686, -14.879 which is\n RA(J2000) = 19h 58m 45s\n Dec(J2000) = -14d 52' 42\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including\nsystematic uncertainty). The BAT light curve showed a multi-peaked\nstructure with a duration of about 20 sec. The peak count rate\nwas ~9000 counts/sec (15-350 keV), at ~0 sec after the trigger.\n\nThe XRT began observing the field at 09:45:00.4 UT, 126.3 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 299.70011, -14.86012\nwhich is equivalent to:\n RA(J2000) = 19h 58m 48.03s\n Dec(J2000) = -14d 51' 36.4\"\nwith an uncertainty of 1.9 arcseconds (radius, 90% containment). This\nlocation is 83 arcseconds from the BAT onboard position, within the BAT\nerror circle. This position may be improved as more data are received;\nthe latest position is available at https://www.swift.ac.uk/sper.\n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (1.24 x\n10^21 cm^-2, Willingale et al. 2013), with an excess column of 3.8\n(+2.62/-2.25) x 10^21 cm^-2 (90% confidence).\n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 129 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers 100% of\nthe XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.\nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nXRT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the expected extinction corresponding to E(B-V) of\n0.183.\n\nBurst Advocate for this burst is M. A. Williams (mjw6837 AT psu.edu).\nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/)\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36208.",
"published": "2024-04-21T10:02:35.846421Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-21T10:02:35.846435Z",
"modified": "2024-04-21T10:02:35.853244Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6787,
"topic": "gcn.circular",
"uuid": "b5ea2b4f-4878-4e19-b0ca-9c940ed5d675",
"title": "EP 240420a: Xinglong decaying optical counterpart",
"submitter": "Hop gcn.circular",
"authors": "Dr Jie Zheng at Xinglong Observatory, National Astronomical Observatories ( NAOC), CAS <jiezheng@nao.cas.cn>",
"data": {
"date": "24/04/21 10:19:24 GMT",
"from": "Dr Jie Zheng at Xinglong Observatory, National Astronomical Observatories ( NAOC), CAS <jiezheng@nao.cas.cn>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36209"
},
"title": "GCN CIRCULAR",
"number": "36209",
"subject": "EP 240420a: Xinglong decaying optical counterpart"
},
"message_text": "B. C. Wang, J. J. Jin, Z. Fan, H. Wu, M. He, H. Y. Mu, L. Ge, J. B. Zhang, J. Zheng, Y. Zhang, X. Li, Y. G. Sun, J. J. Jia, W. X. Li, S. J. Xue, H. Zou, X. N. Guan, D. Xu report on behalf of a large collaboration:\n\nWe observed the field of the X-ray transient, EP 240420a, detected by EP/WXT using the Xinglong 0.8-m telescope located at Xinglong, Hebei, China. We obtained 3 x 600 s clear-band frames with a median time of 2024-04-20T14:48:24, i.e., 2.7 hr after the EP trigger, we luckily found the optical counterpart of EP 240420a in the stacked image. The stacked clear-band image using a 0.8-m telescope has a 3-sigma limiting magnitude of ~ 21 mag, calibrated with the Pan-STARRS g band field. Inspection of the whole EP/WXT 3 arcmin error circle produces a few low S/N optical counterpart candidates. We detected no optical transient candidate during April 20T13:00-15:00 with the 60/90 cm Schmidt Telescope in Xinglong, Hebei, China. The upper limit is ï½19.5 m in the g-band. Then we performed clear-band photometry on the Xinglong 2.16-m telescope located at Xinglong, Hebei, China, and obtained 3x180s clear-band frames with a median time of 2024-04-20T20:20:30, i.e., 8.2 hr after the EP trigger. The stacked clear-band image using the 2.16-m telescope has a 5-sigma limiting magnitude of ~21.7 mag, calibrated with the Pan-STARRS g-band field. Inspection of the whole EP/WXT 3 arcmin error circle produces no optical counterpart candidates.\n\nWithin the 10 arcsec error circle of the EP/FXT, we identified an optical transient (OT) localized at\nR. A. = 15:14:55.072 , Dec. = 14:48:18.096 (J2000).\nThis OT has m = 20.657 +/- 0.4 (AB) in the Xinglong 0.8-m telescope image calibrated with the Pan-STARRS g band field.\n\nWe summarize our observation results as follows:\n\nObs. No. |     Start Time (UTC) | End Time (UTC) | Exposure Time (s) | Apparent mag (AB) | Telescope Name\n1 | 2024-04-20 13:00:00 | 2024-04-20 15:00:00 |  | > 19.5 | Xinglong Schmidt 60/90-cm Telescope\n2 | 2024-04-20 14:38:24 | 2024-04-20 14:58:20 | 3x600 s | 20.657 +/- 0.4 | Xinglong 0.8-m Telescope\n3 | 2024-04-20 20:17:20 | 2024-04-20 20:23:41 | 3x180 s | > 21.7 | Xinglong 2.16-m Telescope\n\nFurther observations are encouraged.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36209.",
"published": "2024-04-21T10:19:43.669312Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-21T10:19:43.669326Z",
"modified": "2024-04-21T10:19:43.678820Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6955,
"topic": "gcn.circular",
"uuid": "80f51463-3a4a-4e87-8ae8-2b0c28540853",
"title": "LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis",
"submitter": "Hop gcn.circular",
"authors": "Tomas Ahumada Mena at Caltech <tahumada@caltech.edu>",
"data": {
"date": "24/04/26 00:25:07 GMT",
"from": "Tomas Ahumada Mena at Caltech <tahumada@caltech.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36310"
},
"title": "GCN CIRCULAR",
"number": "36310",
"subject": "LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis"
},
"message_text": "Tomas Ahumada (Caltech), Robert Stein (Caltech), Vishwajeet Swain (IITB), Anirudh Salgundi (IITB), Aswin Suresh (IITB), Gaurav Waratkar (IITB), Utkarsh Pathak (IITB), Eric Bellm (UW), Mansi Kasliwal (Caltech), Avery Wold (IPAC), Shreya Anand (Caltech), Viraj Karambelkar (Caltech), Theophile du Laz (Caltech), Simeon Reusch (DESY), Igor Andreoni (UMD), Varun Bhalerao (IITB), Brad Cenko (UMD), Michael Coughlin (UMN), David Kaplan (UWM), Jannis Necker (DESY), D. Perley (LJMU), Jesper Sollerman (OKC) report on behalf of the ZTF and GROWTH collaborations:\n\nWe continued observations of S240422ed (GCN 36236) with the Palomar 48-inch telescope equipped with the 47 square-degree Zwicky Transient Facility (ZTF) camera (Graham et al., 2019; Bellm et al., 2019). In total, we covered 59.6% (189.5 sq deg) of the reported localization region at least twice. Our observations were 300s, and reached a median depth of 19.2 in g-band, 19.7 in r-band and 20.3 in i-band. The detailed map of our coverage was reported to TreasureMap (Wyatt et al. 2020).\n\nWe queried the ZTF alert stream using Kowalski (Duev et al. 2019) through Fritz (Coughlin et al. 2023), emgwcave (Karambelkar et al. in prep), and AMPEL (Nordin et al. 2019). We required at least 2 detections separated by at least 15 minutes to select against moving objects. Furthermore, we cross-match our candidates with the Minor Planet Center to flag known asteroids, reject stellar sources (Tachibana and Miller 2018 and using the GAIA catalog), and apply machine learning algorithms (Mahabal et al. 2019). We require that no spatially coincident ZTF alerts were issued before the detection time of the LVK trigger. We also ran forced photometry (FP) on ZTF images (Masci et al. 2019), requested ATLAS FP (Shingles et al. 2021), and require no detections before the LVK trigger.\n\nWe find no new candidate counterparts using ZTF data.\n\nWe also analyse candidate counterparts already reported by the Pan-STARRS and BlackGEM/MeerLICHT collaborations (GCN 36303 and GCN 36307):\n\nTNS Name | Comment\nAT2024hfu | Also detected as ZTF24aakvqha, M~-18 mag (r-band) using NED photz = 0.092748. We confirm the lack of evolution in the r-band.\nAT2024hga | We find multiple ATLAS FP pre-detections (SNR 5-60) at the source location. There are no ZTF FP pre-detections in the last 12 months.\nAT2024hgb | We find multiple ATLAS FP pre-detections (SNR 4-50) at the source location. There are no ZTF FP pre-detections in the last 6 months. M~-19.8 mag (P1 z-band) using NED photz = 0.099940 (475 Mpc). \nAT2024hdl | We find multiple ATLAS FP pre-detections (SNR 4-120) at the source location. There are no ZTF FP pre-detections in the last 12 months. M~-17.3 mag (DECam z-band) using NED photz = 0.0552 (255 Mpc).\nAT2024hgc | ATLAS FP pre-detections (SNR 10-50). There are no ZTF FP pre-detections in the last 12 months.\nAT2024hfx | Also detected as ZTF21aawlmgc, there are multiple ATLAS and ZTF FP detections. Classified in PS1 STRM as QSO.\nAT2024hfo | ATLAS FP pre-detections (SNR 10-100). There are no ZTF FP pre-detections in the last 12 months. \nAT2024hft | Multiple ATLAS FP pre-detections (SNR 4-9). M~-18.9 mag (P1 z-band) using NED photz = 0.091 (430 Mpc). There are no ZTF FP pre-detections in the last 12 months.\nAT 2024hgl | Pre-detections in ATLAS FP (SNR 4-19, latest in 2024-01-07 and 2024-03-18), and in ZTF (2023-11-10). \n\nWe therefore disfavour all these candidates as potential counterparts. \n\nZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges the generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski (Duev et al. 2019). The GROWTH India Telescope (GIT, Kumar et al., 2022) is set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. Its operations are partially supported by funding from the IIT Bombay alumni batch of 1994. The Fritz and SkyPortal projects acknowledge the generous support of The Gordon and Betty Moore Foundation.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36310.",
"published": "2024-04-26T00:25:26.365191Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-26T00:25:26.365218Z",
"modified": "2024-04-26T00:25:26.373099Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6800,
"topic": "gcn.circular",
"uuid": "69ec164b-4b47-4789-9f8d-22dbcf1875e3",
"title": "GRB 240421B: Swift/UVOT Upper Limits",
"submitter": "Hop gcn.circular",
"authors": "Paul Kuin at MSSL <npkuin@gmail.com>",
"data": {
"date": "24/04/21 19:04:49 GMT",
"from": "Paul Kuin at MSSL <npkuin@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36214"
},
"title": "GCN CIRCULAR",
"number": "36214",
"subject": "GRB 240421B: Swift/UVOT Upper Limits"
},
"message_text": "N. P. M. Kuin (UCL-MSSL) and M. Williams (PSU)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 240421B\n130s after the BAT trigger (Williams et al., GCN Circ. 36208). No\noptical afterglow consistent with the XRT position Beardmore et al.\n(GCN Circ. 36213) is detected in the initial UVOT exposures.\nPreliminary 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first\nfinding chart (FC) exposure and subsequent exposures are:\n\nFilter T_start(s) T_stop(s) Exp(s) Mag\n\nwhite_FC 130 279 148 >20.6\nu_FC 343 592 246 >20.2\nwhite 130 1708 218 >20.9\nv 672 1764 78 >18.4\nb 598 1854 84 >19.8\nu 343 1827 339 >20.2\nw1 721 1813 78 >19.4\nw2 648 1568 78 >18.8\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.182 in the direction of the burst\n(Schlegel et al. 1998).\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36214.",
"published": "2024-04-21T19:05:06.953555Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-21T19:05:06.953587Z",
"modified": "2024-04-21T19:05:06.961373Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6801,
"topic": "gcn.circular",
"uuid": "e920f0b1-d2b7-4518-8c6b-edd8673a146a",
"title": "GRB 240421B: J-band upper limits from WINTER",
"submitter": "Hop gcn.circular",
"authors": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"data": {
"date": "24/04/21 19:08:39 GMT",
"from": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36215"
},
"title": "GCN CIRCULAR",
"number": "36215",
"subject": "GRB 240421B: J-band upper limits from WINTER"
},
"message_text": "Viraj Karambelkar (Caltech), Geoffrey Mo (MIT), Robert Stein (Caltech),\nDanielle Frostig (MIT), Tomas Ahumada (Caltech), Nathan Lourie (MIT),\nRobert Simcoe (MIT), Mansi Kasliwal (Caltech)\n\nWe observed the field of the long GRB 240421B (GCN 36208, 36213, 36214) in\nthe near-IR J-band with the WINTER camera on the Palomar 40-inch telescope.\nOur observations started at UTC 2024-04-19T11:16:00 (~1.5 hours since\ntrigger) and lasted for an hour.\n\nThe images were processed through the WINTER data reduction pipeline\nimplemented using mirar (https://zenodo.org/records/10888437) with image\nsubtraction performed relative to reference images built from the VISTA\nHemisphere Survey (McMahon et al. 2013).\n\n\n\nWe do not detect any source at the location of the X-ray counterpart\n(reported in GCN 36213) to a limit of m_J = 19.5 mag (AB, not corrected for\nGalactic extinction). No other new sources are found within the 3 arcmin\nlocalization of the GRB.\n\nWINTER (Wide-field INfrared Transient ExploreR) is a partnership between\nMIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF\nAAG, the David and Lucille Packard Foundation, and the MIT Kavli Institute\nfor Astrophysics and Space Research\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36215.",
"published": "2024-04-21T19:08:47.204329Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-21T19:08:47.204346Z",
"modified": "2024-04-21T19:08:47.209777Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6807,
"topic": "gcn.circular",
"uuid": "cc219fe9-5fef-4b51-ae64-48bcde2c78c7",
"title": "GRB 240421B: Swift-XRT refined Analysis",
"submitter": "Hop gcn.circular",
"authors": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"data": {
"date": "24/04/21 22:50:00 GMT",
"from": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36217"
},
"title": "GCN CIRCULAR",
"number": "36217",
"subject": "GRB 240421B: Swift-XRT refined Analysis"
},
"message_text": "J.P. Osborne (U. Leicester), B. Sbarufatti (INAF-OAB), C. Salvaggio\n(INAF-OAB), M. Ferro (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU),\nA. Tohuvavohu (U. Toronto), K.L. Page (U. Leicester), A.P. Beardmore\n(U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team:\n\nWe have analysed 6.6 ks of XRT data for GRB 240421B, from 110 s to 36.0\nks after the BAT trigger. The data comprise 42 s in Windowed Timing\n(WT) mode (the first 9 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode.\n\nThe light curve can be modelled with an initial power-law decay with an\nindex of alpha=0.50 (+/-0.07), followed by a break at T+2500 s to an\nalpha of 1.20 (+/-0.10).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.87 (+/-0.13). The\nbest-fitting absorption column is 6.5 (+1.0, -0.9) x 10^21 cm^-2, in\nexcess of the Galactic value of 1.2 x 10^21 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum is 4.6 x 10^-11 (7.3 x 10^-11) erg\ncm^-2 count^-1.\n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t 6.5 (+1.0, -0.9) x 10^21 cm^-2\nGalactic foreground: 1.2 x 10^21 cm^-2\nExcess significance: 9.6 sigma\nPhoton index:\t 1.87 (+/-0.13)\n\nIf the light curve continues to decay with a power-law decay index of\n1.20, the count rate at T+24 hours will be 0.023 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x\n10^-12 (1.7 x 10^-12) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01223470.\n\nThis circular is an official product of the Swift-XRT team.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36217.",
"published": "2024-04-21T22:50:15.182460Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-21T22:50:15.182475Z",
"modified": "2024-04-21T22:50:15.190916Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6808,
"topic": "gcn.circular",
"uuid": "b87c16c3-b6ce-4e95-aaa2-5d5811af32d1",
"title": "GRB 240421B: Fermi GBM Observation",
"submitter": "Hop gcn.circular",
"authors": "Cori Fletcher at USRA <cfletcher@usra.edu>",
"data": {
"date": "24/04/21 23:05:42 GMT",
"from": "Cori Fletcher at USRA <cfletcher@usra.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36218"
},
"title": "GCN CIRCULAR",
"number": "36218",
"subject": "GRB 240421B: Fermi GBM Observation"
},
"message_text": "C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 09:42:41.91 UT on 21 April 2024, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 240421B (trigger 735385366/240421405).\nwhich was also detected by Swift BAT (M. A. Williams et al. 2024, GCN 36208).\nThe Fermi GBM on-ground location is consistent with the Swift BAT position.\n\nThe angle from the Fermi LAT boresight is 29 degrees.\n\nThe GBM light curve consists of multiple peaks with a duration (T90)\nof about 12.3 s (50-300 keV). The time-averaged spectrum\nfrom T0+0.003 to T0+18.4 s is best fit by\na Band function with Epeak = 141 +/- 8 keV,\nalpha = -0.91 +/- 0.04, and beta = -2.31 +/- 0.09.\n\nThe event fluence (10-1000 keV) in this time interval is\n(1.28 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+12 s in the 10-1000 keV band is 31.9 +/- 0.5 ph/s/cm^2.\n\nThe spectral analysis results presented above are preliminary;\nfinal results will be published in the GBM GRB Catalog:\nhttps://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html\n\nFor Fermi GBM data and info, please visit the official Fermi GBM Support Page:\nhttps://fermi.gsfc.nasa.gov/ssc/data/access/gbm/\"\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36218.",
"published": "2024-04-21T23:05:56.742591Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-21T23:05:56.742607Z",
"modified": "2024-04-21T23:05:56.751293Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6816,
"topic": "gcn.circular",
"uuid": "f208edbe-4ad3-4f44-b1d1-6a615192d298",
"title": "GRB 240422A: Fermi GBM Final Real-time Localization",
"submitter": "Hop gcn.circular",
"authors": "Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>",
"data": {
"date": "24/04/22 02:51:32 GMT",
"from": "Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36222"
},
"title": "GCN CIRCULAR",
"number": "36222",
"subject": "GRB 240422A: Fermi GBM Final Real-time Localization"
},
"message_text": "The Fermi GBM team reports the detection of a likely LONG GRB\n\nAt 02:40:59 UT on 22 Apr 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240422A (trigger 735446464.467214 / 240422112).\n\nThe on-ground calculated location, using the Fermi GBM trigger data, is RA = 255.6, Dec = -67.4 (J2000 degrees, equivalent to J2000 17h 02m, -67d 24'), with a statistical uncertainty of 9.9 degrees.\n\nThe angle from the Fermi LAT boresight is 23.0 degrees.\n\nThe skymap can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240422112/quicklook/glg_skymap_all_bn240422112.png\n\nThe HEALPix FITS file, including the estimated localization systematic, can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240422112/quicklook/glg_healpix_all_bn240422112.fit\n\nThe GBM light curve can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240422112/quicklook/glg_lc_medres34_bn240422112.gif\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36222.",
"published": "2024-04-22T02:51:47.094781Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T02:51:47.094793Z",
"modified": "2024-04-22T02:51:47.101898Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6817,
"topic": "gcn.circular",
"uuid": "c376152d-f353-43d4-8e4e-fce32970560b",
"title": "GRB 240421B: AstroSat CZTI detection",
"submitter": "Hop gcn.circular",
"authors": "Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>",
"data": {
"date": "24/04/22 04:47:37 GMT",
"from": "Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36223"
},
"title": "GCN CIRCULAR",
"number": "36223",
"subject": "GRB 240421B: AstroSat CZTI detection"
},
"message_text": "G. Waratkar (IITB), J. Joshi (IUCAA), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:\n\nAnalysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 240421B which was also detected by Swift-BAT (Williams et al., GCN Circ. 36208) and Fermi-GBM (Fletcher et al., GCN Circ. 36218).\n\nThe source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-04-21 09:42:54.5 UTC. The measured peak count rate associated with the burst is 368 (+44, -52) counts/s above the background in the combined data of all quadrants, with a total of 843 (+148, -223) counts. The local mean background count rate was 474 (+5, -4) counts/s. Using cumulative rates, we measure a T90 of 6.3 (+3.2, -2.7) s.\n\nIt was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-04-21 09:42:53.8 UTC. The measured peak count rate is 745 (+82, -87) counts/s above the background in the combined Veto data of all quadrants, with a total of 1802 (+268, -278) counts. The local mean background count rate was 1740 (+7, -8) counts/s. We measure a T90 of 5.6 (+1.6, -1.7) s from the cumulative Veto light curve.\n\nCZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.\n\nCZTI GRB detections are reported regularly on the payload site at:\nhttp://astrosat.iucaa.in/czti/?q=grb\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36223.",
"published": "2024-04-22T04:47:53.214775Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T04:47:53.214796Z",
"modified": "2024-04-22T04:47:53.220637Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6818,
"topic": "gcn.circular",
"uuid": "fcb7c614-802d-4619-a0aa-77f692284adb",
"title": "Fermi GRB 240422A: Global MASTER-Net observations report",
"submitter": "Hop gcn.circular",
"authors": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"data": {
"date": "24/04/22 05:31:57 GMT",
"from": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36224"
},
"title": "GCN CIRCULAR",
"number": "36224",
"subject": "Fermi GRB 240422A: Global MASTER-Net observations report"
},
"message_text": "V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,\nG.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij\n(Lomonosov Moscow State University, SAI, Physics Department),\n\nR. Podesta, C.Lopez, F. Podesta, C.Francile\n(Observatorio Astronomico Felix Aguilar OAFA),\n\nR. Rebolo, M. Serra\n(The Instituto de Astrofisica de Canarias),\n\nD. Buckley\n(South African Astronomical Observatory),\n\nO.A. Gress, N.M. Budnev, O.Ershova\n(Irkutsk State University, API),\n\nL.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,\nA.R.Corella, L.H.Rodriguez\n(INAOE, Guillermo Haro Astrophysics Observatory),\n\nA. Tlatov, D. Dormidontov\n(Kislovodsk Solar Station of the Pulkovo Observatory),\n\nV. Yurkov, A. Gabovich\n(Blagoveschensk Educational State University)\n\nMASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 240422A ( Fermi GBM team, GCN 36222) errorbox 2591 sec after notice time and 2626 sec after trigger time at 2024-04-22 03:24:46 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 45 deg. The sun altitude is -21.7 deg.\n\nThe galactic latitude b = -16 deg., longitude l = 324 deg.\n\n\nReal time updated cover map and OT discovered available here:\nhttps://master.sai.msu.ru/site/master2/observ.php?id$30987\n\nWe obtain a following upper limits.\n\nTmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment\n_________|_____________________|_____________________|____________________________________|_____|_______|_______|________\n\n 2657 | 2024-04-22 03:24:46 | MASTER-SAAO | (18h 35m 02.79s , -76d 43m 27.3s) | C | 60 | 19.1 |\n 3878 | 2024-04-22 03:45:07 | MASTER-SAAO | (18h 35m 34.85s , -76d 42m 39.4s) | C | 60 | 18.0 |\n 4038 | 2024-04-22 03:47:47 | MASTER-SAAO | (16h 59m 17.39s , -67d 19m 40.0s) | C | 60 | 18.8 |\n 4038 | 2024-04-22 03:47:47 | MASTER-SAAO | (16h 54m 35.38s , -67d 06m 21.1s) | C | 60 | 19.1 |\n 4118 | 2024-04-22 03:49:07 | MASTER-SAAO | (16h 57m 08.53s , -68d 58m 52.2s) | C | 60 | 19.3 |\n 4118 | 2024-04-22 03:49:07 | MASTER-SAAO | (17h 02m 14.07s , -69d 12m 12.4s) | C | 60 | 19.1 |\n 4198 | 2024-04-22 03:50:27 | MASTER-SAAO | (16h 53m 26.59s , -65d 11m 30.9s) | C | 60 | 19.1 |\n 4198 | 2024-04-22 03:50:27 | MASTER-SAAO | (16h 57m 48.08s , -65d 24m 47.4s) | C | 60 | 18.9 |\n 4277 | 2024-04-22 03:51:46 | MASTER-SAAO | (17h 33m 33.47s , -67d 07m 02.3s) | C | 60 | 19.4 |\nFilter C is a clear (unfiltred) band.\n\n\nThe observation and reduction will continue.\nThe message may be cited.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36224.",
"published": "2024-04-22T05:32:12.279411Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T05:32:12.279428Z",
"modified": "2024-04-22T05:32:12.284370Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6819,
"topic": "gcn.circular",
"uuid": "4fc3d5bf-8f85-4197-a392-8b466c945c36",
"title": "GRB 240415A: Swift-XRT refined Analysis",
"submitter": "Hop gcn.circular",
"authors": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"data": {
"date": "24/04/22 07:22:59 GMT",
"from": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36225"
},
"title": "GCN CIRCULAR",
"number": "36225",
"subject": "GRB 240415A: Swift-XRT refined Analysis"
},
"message_text": "P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:\n\nWe have analysed 5.4 ks of XRT data for GRB 240415A, from 3.3 ks to\n26.8 ks after the BAT trigger. The data comprise 281 s in Windowed\nTiming (WT) mode with the remainder in Photon Counting (PC) mode.\n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=0.97 (+/-0.09).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.18 (+/-0.16). The\nbest-fitting absorption column is 2.2 (+/-0.5) x 10^21 cm^-2, in\nexcess of the Galactic value of 2.5 x 10^20 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum is 3.3 x 10^-11 (4.9 x 10^-11) erg\ncm^-2 count^-1.\n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t 2.2 (+/-0.5) x 10^21 cm^-2\nGalactic foreground: 2.5 x 10^20 cm^-2\nExcess significance: 6.4 sigma\nPhoton index:\t 2.18 (+/-0.16)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01221874.\n\nThis circular is an official product of the Swift-XRT team.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36225.",
"published": "2024-04-22T07:23:15.873194Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T07:23:15.873207Z",
"modified": "2024-04-22T07:23:15.878563Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6820,
"topic": "gcn.circular",
"uuid": "81c5b64c-84cb-44ca-8103-180a503cda0d",
"title": "GRB 240415B: Swift-XRT observations",
"submitter": "Hop gcn.circular",
"authors": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"data": {
"date": "24/04/22 07:23:17 GMT",
"from": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36226"
},
"title": "GCN CIRCULAR",
"number": "36226",
"subject": "GRB 240415B: Swift-XRT observations"
},
"message_text": "J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U.\nLeicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E.\nAmbrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC &\nINAF-OAR), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) reports on\nbehalf of the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nSwift/BAT-detected burst GRB 240415B, collecting 3.4 ks of Photon\nCounting (PC) mode data between T0+86.1 ks and T0+115.2 ks.\n\nFour uncatalogued X-ray sources have been detected consistent with\nbeing within 493 arcsec of the Swift/BAT position, however none of them\nis above the RASS limit or shows definitive signs of fading. Therefore,\nat the present time we cannot identify which, if any, is the afterglow.\nDetails of these sources are given below:\n\nSource 2:\n RA (J2000.0): 132.2001 = 08:48:48.03\n Dec (J2000.0): -27.0714 = -27:04:17.2\n Error: 6.4 arcsec (radius, 90% conf.)\n Count-rate: (9.5 [+10.4, -8.3])e-4 ct s^-1\n Distance: 374 arcsec from Swift/BAT position.\n\nSource 3:\n RA (J2000.0): 132.3176 = 08:49:16.23\n Dec (J2000.0): -27.1553 = -27:09:19.0\n Error: 6.6 arcsec (radius, 90% conf.)\n Count-rate: (2.6 [+1.6, -1.3])e-3 ct s^-1\n Distance: 306 arcsec from Swift/BAT position.\n Flux: (1.32 [+0.83, -0.68])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 6:\n RA (J2000.0): 132.3018 = 08:49:12.44\n Dec (J2000.0): -27.1242 = -27:07:27.0\n Error: 5.5 arcsec (radius, 90% conf.)\n Count-rate: (3.4 [+1.6, -1.3])e-3 ct s^-1\n Distance: 200 arcsec from Swift/BAT position.\n Flux: (4.6 [+2.2, -1.8])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 7:\n RA (J2000.0): 132.4111 = 08:49:38.66\n Dec (J2000.0): -27.0674 = -27:04:02.8\n Error: 5.6 arcsec (radius, 90% conf.)\n Count-rate: (3.6 [+1.8, -1.5])e-3 ct s^-1\n Distance: 301 arcsec from Swift/BAT position.\n Flux: (8.8 [+4.5, -3.6])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nThree uncatalogued sources were also detected too far from the GRB\nposition to be likely afterglow candidates.\n\nThe results of the XRT-team automatic analysis of the XRT observations,\nincluding a position-specific upper limit calculator, are available at\nhttps://www.swift.ac.uk/ToO_GRBs/00021684.\n\nThis circular is an official product of the Swift-XRT team.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36226.",
"published": "2024-04-22T07:23:22.902705Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T07:23:22.902723Z",
"modified": "2024-04-22T07:23:22.906015Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6825,
"topic": "gcn.circular",
"uuid": "bb9bb690-cf05-4024-b153-f598d33ef62b",
"title": "GRB 240419B : MITSuME Akeno optical upper limits",
"submitter": "Hop gcn.circular",
"authors": "Narikazu Higuchi at Tokyo Tech <higuchi@hp.phys.titech.ac.jp>",
"data": {
"date": "24/04/22 11:00:03 GMT",
"from": "Narikazu Higuchi at Tokyo Tech <higuchi@hp.phys.titech.ac.jp>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36227"
},
"title": "GCN CIRCULAR",
"number": "36227",
"subject": "GRB 240419B : MITSuME Akeno optical upper limits"
},
"message_text": "N. Higuchi, Y. Kubo, S. Joshima, H. Hagio, I. Takahashi, M. Sasada, M. Niwano, S. Hayatsu, H. Seki, Y. Yatsu and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:\n\nWe observed the field of GRB 240419B (Dichiara et al., GCN 36180) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno.\n\nThe observation started at 2024-04-19 17:46:23 UT (5.4 hrs after the Swift/BAT trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the enhanced Swift/XRT error region (Osborne et al., GCN 36186), despite the detection report of Daniele et al., (GCN 36191). We obtained the 5-sigma limits of the stacked images as follows.\n\nT0+[hrs] | MID-UT | T-EXP[sec] | 5-sigma limits\n------------------------------------------------------------------------------------------------\n6.4 | 2024-04-19 18:44:10.13 | 3660 | g'>18.6, Rc>18.8, Ic>18.4\n------------------------------------------------------------------------------------------------\nT0+ : Elapsed time after the trigger\nT-EXP: Total Exposure time\n\nWe used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ; https://github.com/MNiwano/Eclaire).\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36227.",
"published": "2024-04-22T11:00:18.198235Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T11:00:18.198247Z",
"modified": "2024-04-22T11:00:18.204993Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6826,
"topic": "gcn.circular",
"uuid": "cf3fc92f-0321-4ba5-a371-c882d670f9cb",
"title": "GRB 240414A: LBT optical detection",
"submitter": "Hop gcn.circular",
"authors": "Andrea Rossi at INAF <andrea.rossi@inaf.it>",
"data": {
"date": "24/04/22 14:43:25 GMT",
"from": "Andrea Rossi at INAF <andrea.rossi@inaf.it>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36228"
},
"title": "GCN CIRCULAR",
"number": "36228",
"subject": "GRB 240414A: LBT optical detection"
},
"message_text": "A. Rossi, E. Maiorano, E. Palazzi (INAF-OAS), M . De Pasquale (Univ. of Messina), report on behalf of the CIBO collaboration:\n\nWe observed the field of GRB 240414A (Caputo et al. GCN 36083) simultaneously in the blue and red arms with the g'-, r'-, and z'-bands with the MODS instrument mounted on LBT (Mt Graham, AZ, USA). Observations were obtained at the midtime 05:41 UT on 2024-04-14, 3 hours and 20 minutes after the burst trigger.\n\nWe detect the optical transient (Schneider et al., GCN 36084, Aryan et al., GCN 36094, Dutton et al., GCN 36097, Xu et al., GCN 36105, Pankov et al., GCN 36113, Wang et al., GCN 36131) in all bands and we measure a preliminary AB magnitudes r'\u0019.1+-0.1, calibrated against SDSS field stars, and not corrected for the foreground Galactic extinction.\n\nWe acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly A. Cardwell, J. Williams, F. Cusano and D. Paris, in obtaining these observations.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36228.",
"published": "2024-04-22T14:43:41.651707Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T14:43:41.651727Z",
"modified": "2024-04-22T14:43:41.658296Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6827,
"topic": "gcn.circular",
"uuid": "4467bb41-6b9b-4f49-8989-b4d9e4f8fab6",
"title": "GRB 240414A: AMI-LA radio observations",
"submitter": "Hop gcn.circular",
"authors": "Lauren Rhodes at Oxford <lauren.rhodes@physics.ox.ac.uk>",
"data": {
"date": "24/04/22 15:06:17 GMT",
"from": "Lauren Rhodes at Oxford <lauren.rhodes@physics.ox.ac.uk>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36229"
},
"title": "GCN CIRCULAR",
"number": "36229",
"subject": "GRB 240414A: AMI-LA radio observations"
},
"message_text": "Lauren Rhodes, Rob Fender (Oxford), Dave Green, Dave Titterington (Cambridge) report:\n\nWe observed the field of the afterglow candidate GRB 240414A (GCN #36083) with the Arcminute Microkelvin Imager Large-Array (AMI-LA) at 15.5 GHz beginning at 18:54UT on 20-Apr-2024 for a total of 4 hours. The flux standard 3c286 was used to calibrate the bandpass response and flux scale of the AMI-LA and J1219+4829 was used as an interleaved complex gain calibrator.\n\nWe do not detect any radio emission at the position of the afterglow candidate as reported in GCN #36102 at a 3 sigma upper limit of 297uJy/beam.\n\nWe thank the staff at the Mullard Radio Astronomy Observatory for carrying out these observations and operating the AMI-LA.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36229.",
"published": "2024-04-22T15:06:34.611730Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T15:06:34.611747Z",
"modified": "2024-04-22T15:06:34.617717Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6830,
"topic": "gcn.circular",
"uuid": "d4232273-c0ee-45ea-a8b2-df614b09dcdf",
"title": "Fermi-LAT gamma-ray observations of IceCube-240419A",
"submitter": "Hop gcn.circular",
"authors": "chiara.bartolini-1@unitn.it",
"data": {
"date": "24/04/22 16:20:44 GMT",
"from": "chiara.bartolini-1@unitn.it",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36230"
},
"title": "GCN CIRCULAR",
"number": "36230",
"subject": "Fermi-LAT gamma-ray observations of IceCube-240419A"
},
"message_text": "C. Bartolini (INFN Bari), S. Garrappa (Weizmann Institute of Science), S. Buson (DESY; Univ. of Wuerzburg), L. Pfeiffer (Univ. of Wuerzburg) and J. Sinapius (DESY) on behalf of the Fermi-LAT collaboration:\n\nWe report an analysis of observations of the vicinity of the high-energy IC240419A neutrino event (GCN 36196) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2024-04-19 at 23:25:41.05 UT (T0) with J2000 position RA = 73.17 (+2.60, -3.74) deg, Decl. = +1.64 (+1.27, -1.09) deg (90% PSF containment). There is one cataloged gamma-ray (>100 MeV; The Fermi-LAT collaboration 2022, ApJS, 260, 53) source located within the 90% IC240419A localization region. This is 4FGL J0502.6+0036, located at 2.69 degrees from the best-fit neutrino position. Based on a preliminary analysis of the LAT data over the timescales of 1-month and 1-day prior to T0, this object is not significantly detected (> 5 sigma).\n\nWe searched for intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (> 5 sigma) new excess emission (> 100 MeV) at the IC240419A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC240419A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 5.98e-10 ph cm^-2 s^-1 for ~15-years (2008-08-04 to 2024-04-19 UTC), and < 1.33e-8 (< 1.24e-7) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0.\n\nSince Fermi normally operates in an all-sky scanning mode, regular monitoring of this region will continue. For this observation the Fermi-LAT contact person is C. Bartolini (chiara.bartolini at ba.infn.it).\n\nThe Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36230.",
"published": "2024-04-22T16:21:00.063995Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T16:21:00.064019Z",
"modified": "2024-04-22T16:21:00.128910Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6831,
"topic": "gcn.circular",
"uuid": "bbec57be-2ee1-4800-a80f-5142e5e3af17",
"title": "GRB 240414A: radio detection with the VLA",
"submitter": "Hop gcn.circular",
"authors": "Stefano Giarratana at University of Bologna <s.giarratana@ira.inaf.it>",
"data": {
"date": "24/04/22 16:59:02 GMT",
"from": "Stefano Giarratana at University of Bologna <s.giarratana@ira.inaf.it>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36231"
},
"title": "GCN CIRCULAR",
"number": "36231",
"subject": "GRB 240414A: radio detection with the VLA"
},
"message_text": "S. Giarratana (INAF-OAB), M. Giroletti (INAF-IRA),\nG. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),\nN. Omodei (Stanford Univ.)\n\nAt 01:42:45 UT on 2024 April 17 (T_mid = 2.99 days post-burst) the\nKarl G. Jansky VLA started observing the field of GRB 240414A\n(Caputo et al., GCN 36083) at a central frequency of 6 and 10 GHz.\n\nThe standard J1331+3030 (3C286) was used as bandpass and flux density\ncalibrator, while J1217+5835 was used as complex gain calibrator.\n\nFrom a preliminary analysis, an unresolved radio source is clearly\ndetected at both frequencies at a position:\n\nRA: 12:19:08.08 +- 0.01\nDec: +56:44:28.7 +- 0.2\n\nThe surface brightness peak is 40 uJy/beam and 60 uJy/beam at 6\nand 10 GHz, respectively. The r.m.s. noise level of the images is\n7 uJy/beam at both 6 and 10 GHz.\n\nThe synthesized beams are 4.1 x 3.0 arcsec (PA: 70deg) at 6 GHz\nand 2.7 x 1.9 arcsec (PA: 76deg) at 10 GHz.\n\nWhile no source is detected at the aforementioned position in previous\nradio surveys (FIRST, NVSS, VLASS), their r.m.s. noise levels (1sigma)\nis above 100 uJy/b, well above the derived surface brightness peak.\nTherefore, we cannot exclude the contribution from the GRB host galaxy yet.\n\nWe would like to thank the staff of the VLA for approving, executing,\nand processing the observations.\n\nThe National Radio Astronomy Observatory is a facility of the National\nScience Foundation operated under cooperative agreement by Associated\nUniversities, Inc.\n\nThese observations were carried out as part of project SF161095,\napproved in the framework of the Fermi - NRAO joint program agreement.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36231.",
"published": "2024-04-22T16:59:18.130489Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T16:59:18.130505Z",
"modified": "2024-04-22T16:59:18.137463Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6834,
"topic": "gcn.circular",
"uuid": "09d382d6-fa8b-475c-9603-c0f16ca5c97d",
"title": "GRB 240421A: Glowbug gamma-ray detection",
"submitter": "Hop gcn.circular",
"authors": "C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>",
"data": {
"date": "24/04/22 18:09:31 GMT",
"from": "C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36232"
},
"title": "GCN CIRCULAR",
"number": "36232",
"subject": "GRB 240421A: Glowbug gamma-ray detection"
},
"message_text": "C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report:\n \nThe Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 240421A, which was also detected by Fermi/GBM (GCN 36204).\n \nUsing an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2024-04-21 05:21:56.632 with a duration of 2.0 s and a total significance of about 11.3 sigma. The light curve comprises a double-peaked structure.\n \nThe analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.\n \nGlowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâs STP-H9 to the ISS. The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.\n \n[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959\n[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O\n[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006\n \nDistribution Statement A: Approved for public release. Distribution is unlimited.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36232.",
"published": "2024-04-22T18:09:50.598254Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T18:09:50.598273Z",
"modified": "2024-04-22T18:09:50.607524Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6835,
"topic": "gcn.circular",
"uuid": "4574c084-cdcc-4d33-a1d5-f5d89b2ff1dc",
"title": "Fermi trigger No 735470374: Global MASTER-Net observations report",
"submitter": "Hop gcn.circular",
"authors": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"data": {
"date": "24/04/22 18:31:16 GMT",
"from": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36233"
},
"title": "GCN CIRCULAR",
"number": "36233",
"subject": "Fermi trigger No 735470374: Global MASTER-Net observations report"
},
"message_text": "V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,\nG.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij\n(Lomonosov Moscow State University, SAI, Physics Department),\n\nR. Podesta, C.Lopez, F. Podesta, C.Francile\n(Observatorio Astronomico Felix Aguilar OAFA),\n\nR. Rebolo, M. Serra\n(The Instituto de Astrofisica de Canarias),\n\nD. Buckley\n(South African Astronomical Observatory),\n\nO.A. Gress, N.M. Budnev, O.Ershova\n(Irkutsk State University, API),\n\nL.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,\nA.R.Corella, L.H.Rodriguez\n(INAOE, Guillermo Haro Astrophysics Observatory),\n\nA. Tlatov, D. Dormidontov\n(Kislovodsk Solar Station of the Pulkovo Observatory),\n\nV. Yurkov, A. Gabovich\n(Blagoveschensk Educational State University)\n\nMASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB240422.39 (trigger No 735470374,19h 01m 45.60s , +50d 12m 00.0s, R=2.77) errorbox 14775 sec after notice time and 28066 sec after trigger time at 2024-04-22 17:07:16 UT, with upper limit up to 15.7 mag. Observations started at twilight. The observations began at zenith distance = 79 deg. The sun altitude is -11.9 deg.\n\nThe galactic latitude b = 19 deg., longitude l = 81 deg.\n\n\nReal time updated cover map and OT discovered available here:\nhttps://master.sai.msu.ru/site/master2/observ.php?id$31376\n\nWe obtain a following upper limits.\n\nTmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment\n_________|_____________________|_____________________|____________________________________|_____|_______|_______|________\n\n 28097 | 2024-04-22 17:07:16 | MASTER-Kislovodsk | (19h 08m 50.65s , +50d 36m 56.3s) | C | 60 | 15.4 |\n 28097 | 2024-04-22 17:07:16 | MASTER-Kislovodsk | (19h 15m 01.01s , +50d 11m 53.6s) | C | 60 | 13.8 |\n 28177 | 2024-04-22 17:08:36 | MASTER-Kislovodsk | (18h 51m 07.10s , +50d 10m 54.9s) | C | 60 | 13.9 |\n 28177 | 2024-04-22 17:08:36 | MASTER-Kislovodsk | (18h 44m 56.27s , +50d 35m 51.8s) | C | 60 | 15.7 |\n 28257 | 2024-04-22 17:09:56 | MASTER-Kislovodsk | (19h 08m 01.40s , +52d 30m 37.0s) | C | 60 | 15.5 |\n 28257 | 2024-04-22 17:09:56 | MASTER-Kislovodsk | (19h 14m 28.01s , +52d 05m 33.0s) | C | 60 | 13.4 |\n 28338 | 2024-04-22 17:11:17 | MASTER-Kislovodsk | (18h 47m 50.82s , +48d 42m 28.9s) | C | 60 | 15.5 |\n 28338 | 2024-04-22 17:11:17 | MASTER-Kislovodsk | (18h 53m 46.86s , +48d 17m 25.8s) | C | 60 | 14.0 |\n 28418 | 2024-04-22 17:12:37 | MASTER-Kislovodsk | (19h 16m 46.27s , +48d 17m 45.1s) | C | 60 | 14.2 |\n 28418 | 2024-04-22 17:12:37 | MASTER-Kislovodsk | (19h 10m 50.90s , +48d 42m 59.0s) | C | 60 | 15.5 |\n 28565 | 2024-04-22 17:15:04 | MASTER-Kislovodsk | (18h 42m 58.98s , +52d 31m 29.3s) | C | 60 | 15.6 |\n 28565 | 2024-04-22 17:15:04 | MASTER-Kislovodsk | (18h 49m 26.47s , +52d 06m 28.3s) | C | 60 | 13.4 |\n 28645 | 2024-04-22 17:16:24 | MASTER-Kislovodsk | (18h 57m 36.26s , +46d 23m 15.4s) | C | 60 | 14.4 |\n 28646 | 2024-04-22 17:16:25 | MASTER-Kislovodsk | (18h 51m 53.60s , +46d 48m 25.5s) | C | 60 | 15.5 |\n 28729 | 2024-04-22 17:17:48 | MASTER-Kislovodsk | (19h 08m 16.95s , +54d 22m 53.3s) | C | 60 | 15.6 |\n 28729 | 2024-04-22 17:17:48 | MASTER-Kislovodsk | (19h 15m 01.49s , +53d 57m 44.1s) | C | 60 | 13.4 |\n 28809 | 2024-04-22 17:19:08 | MASTER-Kislovodsk | (18h 49m 04.45s , +53d 58m 32.0s) | C | 60 | 12.6 |\n 29452 | 2024-04-22 17:29:50 | MASTER-Kislovodsk | (19h 08m 50.50s , +50d 37m 29.7s) | C | 60 | 15.6 |\n 29452 | 2024-04-22 17:29:51 | MASTER-Kislovodsk | (19h 15m 02.18s , +50d 12m 38.1s) | C | 60 | 14.4 |\n 29533 | 2024-04-22 17:31:12 | MASTER-Kislovodsk | (18h 45m 01.26s , +50d 36m 59.4s) | C | 60 | 15.6 |\n 29533 | 2024-04-22 17:31:12 | MASTER-Kislovodsk | (18h 51m 13.58s , +50d 12m 14.4s) | C | 60 | 13.9 |\n 29614 | 2024-04-22 17:32:33 | MASTER-Kislovodsk | (19h 07m 57.49s , +52d 29m 24.4s) | C | 60 | 15.4 |\n 29614 | 2024-04-22 17:32:33 | MASTER-Kislovodsk | (19h 14m 25.09s , +52d 04m 32.8s) | C | 60 | 13.6 |\n 29696 | 2024-04-22 17:33:55 | MASTER-Kislovodsk | (18h 47m 57.62s , +48d 42m 21.0s) | C | 60 | 15.4 |\n 29696 | 2024-04-22 17:33:55 | MASTER-Kislovodsk | (18h 53m 54.83s , +48d 17m 33.9s) | C | 60 | 14.2 |\n 29778 | 2024-04-22 17:35:17 | MASTER-Kislovodsk | (19h 10m 56.19s , +48d 43m 09.6s) | C | 60 | 15.4 |\n 29778 | 2024-04-22 17:35:17 | MASTER-Kislovodsk | (19h 16m 52.55s , +48d 18m 12.4s) | C | 60 | 14.4 |\n 29858 | 2024-04-22 17:36:37 | MASTER-Kislovodsk | (18h 43m 05.14s , +52d 30m 24.3s) | C | 60 | 15.3 |\n 29858 | 2024-04-22 17:36:37 | MASTER-Kislovodsk | (18h 49m 33.24s , +52d 05m 38.1s) | C | 60 | 13.4 |\n 29938 | 2024-04-22 17:37:57 | MASTER-Kislovodsk | (18h 51m 55.55s , +46d 49m 40.0s) | C | 60 | 15.1 |\n 29938 | 2024-04-22 17:37:57 | MASTER-Kislovodsk | (18h 57m 39.05s , +46d 24m 48.6s) | C | 60 | 14.4 |\n 30018 | 2024-04-22 17:39:17 | MASTER-Kislovodsk | (19h 08m 18.49s , +54d 24m 21.8s) | C | 60 | 15.3 |\n 30018 | 2024-04-22 17:39:17 | MASTER-Kislovodsk | (19h 15m 04.01s , +53d 59m 26.7s) | C | 60 | 13.5 |\n 30098 | 2024-04-22 17:40:37 | MASTER-Kislovodsk | (18h 49m 03.08s , +54d 01m 18.0s) | C | 60 | 13.1 |\nFilter C is a clear (unfiltred) band.\n\n\nThe observation and reduction will continue.\nThe message may be cited.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36233.",
"published": "2024-04-22T18:31:33.060819Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-22T18:31:33.060845Z",
"modified": "2024-04-22T18:31:33.070402Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6848,
"topic": "gcn.circular",
"uuid": "bfb3d4b6-1e92-4bbb-aa09-e434d6907657",
"title": "LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations",
"submitter": "Hop gcn.circular",
"authors": "Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>",
"data": {
"date": "24/04/23 00:40:03 GMT",
"from": "Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36238"
},
"title": "GCN CIRCULAR",
"number": "36238",
"subject": "LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations"
},
"message_text": "N. Kawai (RIKEN), H. Negoro, M. Nakajima (Nihon U.),\nT. Mihara (RIKEN),\nS. Sugita, M. Serino, Y. Kawakubo, H. Hiramatsu, H. Nishikawa, Y. Kondo (AGU)\nreport on behalf of the MAXI team:\n\nWe examined MAXI/GSC all-sky X-ray images (2-20 keV)\nafter compact binary merger candidate S240422ed at 2024-04-22 21:35:13.417 UTC (GCN #36236).\n\nAt the trigger time of S240422ed, the high-voltage of MAXI/GSC was off,\nand it was turned on at T0+620 sec (+10.3 min).\nThe first one-orbit (92 min) scan observation with GSC after the event covered 100%\nof the 90% credible region of the bayestar skymap from 22:32:11 to 22:37:06 UTC (T0+3418 to T0+3713 sec).\n\nNo significant new source was found in the region in the one-orbit scan observation.\nA typical 1-sigma averaged upper limit obtained in one scan observation\nis 20 mCrab at 2-20 keV.\n\nIf you require information about X-ray flux by MAXI/GSC at specific coordinates,\nplease contact the submitter of this circular by email.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36238.",
"published": "2024-04-23T00:40:20.210559Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T00:40:20.210580Z",
"modified": "2024-04-23T00:40:20.218371Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6849,
"topic": "gcn.circular",
"uuid": "cf7f5acd-7e57-4e27-b89c-c2b08c41b774",
"title": "LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO",
"submitter": "Hop gcn.circular",
"authors": "Samuele Ronchini at PSU <sjs8171@psu.edu>",
"data": {
"date": "24/04/23 02:19:57 GMT",
"from": "Samuele Ronchini at PSU <sjs8171@psu.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36239"
},
"title": "GCN CIRCULAR",
"number": "36239",
"subject": "LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO"
},
"message_text": "Samuele Ronchini (PSU), Gayathri Raman (PSU), Tyler Parsotan (NASA GSFC), Aaron Tohuvavohu (U Toronto), James DeLaunay (PSU), Jamie A. Kennea (PSU) report:\n\nSwift/BAT was observing 60.4% of the GW localization probability (bayestar.multiorder.fits) at merger time. A fraction 6% of the GW localization posterior is contained inside the BAT coded FoV.\n\nThe LVK notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).\n\nUpon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.\n\nUsing the NITRATES analysis (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits.\n\nWe quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins.\nIn units of 10^-7 erg/s/cm^2:\n\ntime_bin (s) soft normal hard GRB170817\n------------------------------------\n0.256 11.3 7.63 7.01 8.25\n1.024 5.78 3.90 3.58 4.22\n4.096 3.13 2.11 1.94 2.29\n16.384 1.98 1.34 1.23 1.44\n\n\n\n\nThe upper limits as function of sky position are plotted here, alongside the GW localization:\nhttps://doi.org/10.5281/zenodo.11043239\nThe solid and dashed lines indicate the 90% and 50% GW contour levels, respectively. The corresponding fits file is also included.\n\nGUANO is a fully autonomous, extremely low latency, spacecraft\ncommanding pipeline designed for targeted recovery of BAT event mode\ndata around the times of compelling astrophysical events to enable\nmore sensitive GRB searches.\n\nA live reporting of Swift/BAT event data recovered by GUANO can be\nfound at: https://www.swift.psu.edu/guano/\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36239.",
"published": "2024-04-23T02:20:14.161652Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T02:20:14.161667Z",
"modified": "2024-04-23T02:20:14.169913Z",
"nonlocalizedevents": [
{
"event_id": "S240421a"
}
],
"targets": []
},
{
"id": 6853,
"topic": "gcn.circular",
"uuid": "bd722178-6a50-4683-a19f-100693b3363c",
"title": "LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification",
"submitter": "Hop gcn.circular",
"authors": "Sylvia Biscoveanu at Northwestern CIERA <sylvia.biscoveanu@ligo.org>",
"data": {
"date": "24/04/23 02:59:52 GMT",
"from": "Sylvia Biscoveanu at Northwestern CIERA <sylvia.biscoveanu@ligo.org>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36240"
},
"title": "GCN CIRCULAR",
"number": "36240",
"subject": "LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification"
},
"message_text": "The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:\n\nWe have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S240422ed (GCN Circular 36236). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline0.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:\n\nhttps://gracedb.ligo.org/superevents/S240422ed\n\nBased on posterior support from parameter estimation [1], under the assumption that the candidate S240422ed is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is >99%. [2] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is >99%. [2] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 34%.\n\nFor the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 272 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis):\n icrs; ellipse(08h13m, -26d38m, 14.43d, 6.01d, 100.20d)\nMarginalized over the whole sky, the a posteriori luminosity distance estimate is 188 +/- 43 Mpc (a posteriori mean +/- standard deviation).\n\nFor further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/.\n\n [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380\n [2] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36240.",
"published": "2024-04-23T03:00:11.508421Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T03:00:11.508456Z",
"modified": "2024-04-23T03:00:11.517737Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6854,
"topic": "gcn.circular",
"uuid": "f6843a8a-8e81-4b24-a344-586ad46d2d22",
"title": "LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations",
"submitter": "Hop gcn.circular",
"authors": "Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>",
"data": {
"date": "24/04/23 03:21:42 GMT",
"from": "Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36241"
},
"title": "GCN CIRCULAR",
"number": "36241",
"subject": "LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations"
},
"message_text": "O.J. Roberts (USRA/NASA-MSFC) reports on behalf of the Fermi-GBM Team:\n\nFor S240422ed (GCN 36240) and using the updated bayestar skymap, Fermi-GBM was observing 100.0% of the localization probability at event time.\n\nThere was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo/KAGRA (LVK) detection of GW trigger S240422ed. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around merger time, and also identified no counterpart candidates.\n\nNo part of the LVK localization region is behind the Earth for Fermi, located at an RA= 08h 13m, Dec.= - 26d 38m with an area of 272 deg2. We therefore set upper limits on impulsive gamma-ray emission for the GW localization region visible to Fermi at merger time. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV, weighted by GW localization probability (in units of 10^-7 erg/s/cm^2):\n\nTimescale Soft Normal Hard\n-----------------------------------------\n0.128 s: 1.8 3.4 7.5\n1.024 s: 0.6 0.9 2.4\n8.192 s: 0.2 0.3 0.9\n\nAssuming the median luminosity distance of 188.2 +/- 43.2 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^48 erg/s):\n\nTimescale Soft Normal Hard\n------------------------------------------\n0.128s: 1.16 2.05 7.42\n1.024s: 0.37 0.54 2.37\n8.192s: 0.11 0.20 0.84\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36241.",
"published": "2024-04-23T03:21:58.186376Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T03:21:58.186389Z",
"modified": "2024-04-23T03:21:58.195729Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6855,
"topic": "gcn.circular",
"uuid": "cc35da83-ef78-4430-861b-d777ef3a3abf",
"title": "LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits",
"submitter": "Hop gcn.circular",
"authors": "Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>",
"data": {
"date": "24/04/23 03:40:26 GMT",
"from": "Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36242"
},
"title": "GCN CIRCULAR",
"number": "36242",
"subject": "LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits"
},
"message_text": "G. Waratkar (IITB), V. Bhalerao (IITB), J. Joshi (IUCAA), M. Tembhurnikar (IUCAA), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:\n\nWe have carried out a search for X-ray candidates in AstroSat-CZTI data in a 100 sec window around the trigger time of the event S240422ed (UTC 2024-04-22 21:35:13, GraceDB event). We use the Bilby.offline0.multiorder.fits map (https://gracedb.ligo.org/api/superevents/S240422ed/files/Bilby.offline0.multiorder.fits) for our analysis. CZTI is a coded aperture mask instrument that has considerable effective area for about 29% of the entire sky, but is also sensitive to brighter transients from the entire sky. At the time of the merger, AstroSat's nominal pointing is RA,DEC = 07:31:19.6, 41:26:42.0 (112.8317,41.4450), which is ~68 deg away from the maximum probability location. At the time of the merger event, the Earth-satellite-transient angle corresponding to maximum probability location is ~123 deg and hence is not occulted by Earth in satellite's frame. In a time interval of 100 sec around the event, the region of the localisation map which is not occulted by Earth in the satellite's frame has a total probability of 1.0 (100%).\n\nCZTI data were de-trended to remove orbit-wise background variation. We then searched data from the four independent, identical quadrants to look for coincident spikes in the count rates. Searches were undertaken by binning the data in 0.1s, 1s, and 10s respectively. Statistical fluctuations in background count rates were estimated by using data from 5 preceding orbits. We selected confidence levels such that the probability of a false trigger in a 100 sec window is 10^-4 (refer arxiv:ââ2402.07564 for more details). \n\nWe do not find any evidence for any hard X-ray transient in this window, in the CZTI energy range of 20-200 keV.\n\nWe use a detailed mass model of the satellite to calculate the direction-dependent instrument response for points in the visible sky. We then assume the source is modelled as a power law with photon index alpha = -1, and convert our count rate upper limits to direction-dependent flux limits. We obtain the following upper limits for source flux in the 20-200 keV band by taking a probability weighted mean over the visible sky:\n\n0.1 s: flux limit= 1.16e-06 ergs/cm^2/s; fluence limit = 1.16e-07 ergs/cm^2\n1.0 s: flux limit= 2.88e-07 ergs/cm^2/s; fluence limit = 2.88e-07 ergs/cm^2\n10.0 s: flux limit= 9.06e-08 ergs/cm^2/s; fluence limit = 9.06e-07 ergs/cm^2\n\nWe note that these limits mean that we are not sensitive to a GW170817-like event at the luminosity distance of 188 Mpc. \n\nCZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.\n\nCZTI GRB detections are reported regularly on the payload site at:\nhttp://astrosat.iucaa.in/czti/?q=emgw\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36242.",
"published": "2024-04-23T03:40:43.511368Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T03:40:43.511382Z",
"modified": "2024-04-23T03:40:43.520198Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6856,
"topic": "gcn.circular",
"uuid": "c066905a-b2b7-4fdf-9296-4562c5d4d7e0",
"title": "LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume",
"submitter": "Hop gcn.circular",
"authors": "David Cook at Caltech/IPAC-NED <dcook@ipac.caltech.edu>",
"data": {
"date": "24/04/23 03:57:16 GMT",
"from": "David Cook at Caltech/IPAC-NED <dcook@ipac.caltech.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36243"
},
"title": "GCN CIRCULAR",
"number": "36243",
"subject": "LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume"
},
"message_text": "\nDavid O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC)\n\nOn behalf of the NASA/IPAC Extragalactic Database (NED) Team.\n\nWe spatially cross-matched the LVK S240422ed-4-Update sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023), which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 1520 galaxies within the 90% containment volume, and we list here the top 20 galaxies located in the 90% volume sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full list of galaxies in the 90% volume go to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/.\n\nThe NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic followup observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D*P_SFR; and specific star formation rate, P_3D*P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume.\n\nThe NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic followup observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D*P_SFR; and specific star formation rate, P_3D*P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume.\n\n| objname| ra| dec|objtype| DistMpc|DistMpc_unc| m_NUV|m_NUV_unc| m_Ks| m_Ks_unc| m_W1| m_W1_unc| P_3D|P_3D_LumW1|\n| | deg| deg| | Mpc| |mag(AB)| | mag| | mag| | Prob| Prob|\n|WISEA J080228.69-291233.8| 120.61954| -29.20947| G| 272.74| null| null| null| 12.564| 0.134| 9.447| 0.006|8.70e-01| 5.43e-03|\n|WISEA J075804.45-271753.4| 119.51854| -27.29842| G| 228.15| null| null| null| 12.116| 0.142| 9.099| 0.006|6.34e-01| 3.77e-03|\n|WISEA J075810.99-274632.0| 119.54587| -27.77561| G| 265.35| null| null| null| 13.392| 0.199| 9.774| 0.006|8.66e-01| 3.70e-03|\n|WISEA J080557.29-264951.2| 121.48858| -26.83086| G| 258.93| null| null| null| 12.567| 0.118| 9.690| 0.006|7.74e-01| 3.21e-03|\n|WISEA J081655.77-312551.2| 124.23242| -31.43092| G| 267.28| null| null| null| 12.612| 0.134| 10.041| 0.008|8.49e-01| 2.82e-03|\n|WISEA J080229.34-264555.8| 120.62217| -26.76550| G| 243.08| null| null| null| 12.816| 0.190| 9.537| 0.006|6.41e-01| 2.77e-03|\n|WISEA J082137.61-213407.8| 125.40692| -21.56906| G| 204.94| null| null| null| 12.428| 0.135| 8.726| 0.005|4.04e-01| 2.48e-03|\n|WISEA J080659.79-404353.6| 121.74875| -40.73136| G| 177.69| null| null| null| 13.387| 0.225| 9.388| 0.006|8.05e-01| 2.32e-03|\n|WISEA J080923.30-310813.9| 122.34713| -31.13725| G| 256.79| null| null| null| 12.688| 0.137| 9.977| 0.008|6.77e-01| 2.20e-03|\n|WISEA J075824.76-341335.8| 119.60313| -34.22664| IrS| 254.57| null| null| null| 11.847| 0.054| 10.262| 0.008|7.87e-01| 2.18e-03|\n|WISEA J075643.03-243439.3| 119.17933| -24.57753| G| 267.14| null| null| null| 11.504| 0.120| 10.327| 0.007|8.60e-01| 2.12e-03|\n|WISEA J080353.50-262427.5| 120.97271| -26.40767| IrS| 265.24| null| null| null| 12.972| 0.194| 10.434| 0.007|8.26e-01| 1.83e-03|\n|WISEA J075840.13-220511.5| 119.66717| -22.08650| G| 218.83| null| null| null| 12.180| 0.109| 9.914| 0.005|7.26e-01| 1.69e-03|\n|WISEA J082138.50-330059.5| 125.41046| -33.01656| G| 261.97| null| null| null| 12.285| 0.102| 10.627| 0.017|8.93e-01| 1.63e-03|\n|WISEA J075349.40-245755.1| 118.45538| -24.96531| G| 240.66| null| null| null| 13.650| 0.228| 10.360| 0.008|8.04e-01| 1.57e-03|\n|WISEA J081226.90-184118.1| 123.11217| -18.68850| G| 248.87| null| null| null| 11.867| 0.074| 10.474| 0.006|8.45e-01| 1.53e-03|\n|WISEA J075941.81-384356.0| 119.92358| -38.73260| G| 177.56| null| null| null| 11.293| 0.017| 9.747| 0.023|7.41e-01| 1.49e-03|\n|WISEA J082808.25-343447.5| 127.03429| -34.57992| G| 137.12| null| null| null| 11.338| 0.144| 9.306| 0.007|7.71e-01| 1.34e-03|\n|WISEA J080917.51-294053.9| 122.32292| -29.68169| G| 260.11| null| null| null| 12.950| 0.154| 10.638| 0.006|7.22e-01| 1.33e-03|\n|WISEA J080158.78-164749.4| 120.49496| -16.79703| G| 192.74| null| null| null| 11.385| 0.102| 10.160| 0.006|8.93e-01| 1.29e-03|\n\nTable 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S240422ed sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D*P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Objtype is the object type of the galaxy candidate. Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1).\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36243.",
"published": "2024-04-23T03:57:31.803084Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T03:57:31.803097Z",
"modified": "2024-04-23T03:57:31.810074Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6865,
"topic": "gcn.circular",
"uuid": "bb50aa97-9dc4-49b8-9799-f1988f0401b4",
"title": "LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations",
"submitter": "Hop gcn.circular",
"authors": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"data": {
"date": "24/04/23 08:10:26 GMT",
"from": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36248"
},
"title": "GCN CIRCULAR",
"number": "36248",
"subject": "LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations"
},
"message_text": "Viraj Karambelkar (Caltech), Geoffrey Mo (MIT), Robert Stein (Caltech),\nNathan Lourie (MIT),\n\nDanielle Frostig (MIT), Tomas Ahumada (Caltech), Robert Simcoe (MIT), and\nMansi Kasliwal (Caltech)\n\nWe observed the localization region of the LVK trigger S240422ed (GCN\n36236) with the 1.2 sq. degree WINTER camera on the Palomar 1-m telescope\n(Lourie et al. 2021). We obtained images in the near-IR J-band of the Bilby\nsky map (GCN 36240). Our observations began at 2024-04-23T03:04 UTC, ~5.5\nhours after the GW event time, and lasted for ~2.5 hours.\n\nOur observations covered ~14% of the localization probability, and achieved\na 5-sigma depth ranging between m_J = 16 - 17 mag (AB) depending on the\nsensor temperature. The observations have been reported to TreasureMap\n(Wyatt et al. 2020).\n\nThe images were processed through the WINTER data reduction pipeline\nimplemented using mirar (https://github.com/winter-telescope/mirar,\nhttps://doi.org/10.5281/zenodo.10888436) We cross-matched all sources with\nthe alert stream from the Zwicky Transient Facility (GCN 36246). We found\n153 candidates and rejected them as variable stars. Further analysis is\nunderway.\n\n\n\nWINTER (Wide-field INfrared Transient ExploreR) is a partnership between\nMIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF\nAAG, the David and Lucille Packard Foundation, and the MIT Kavli Institute\nfor Astrophysics and Space Research.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36248.",
"published": "2024-04-23T08:10:41.873298Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T08:10:41.873321Z",
"modified": "2024-04-23T08:10:41.884601Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6866,
"topic": "gcn.circular",
"uuid": "fd2b9b9d-e93d-4eed-926c-0c20429192ec",
"title": "GRB 240421B: ATCA radio observations",
"submitter": "Hop gcn.circular",
"authors": "Gemma Anderson at Curtin U <gemma.anderson@curtin.edu.au>",
"data": {
"date": "24/04/23 09:50:08 GMT",
"from": "Gemma Anderson at Curtin U <gemma.anderson@curtin.edu.au>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36249"
},
"title": "GCN CIRCULAR",
"number": "36249",
"subject": "GRB 240421B: ATCA radio observations"
},
"message_text": "G. E. Anderson (Curtin University), L. Rhodes (U. Oxford), J. K. Leung (U. Toronto/HUJI), S. Chastain (UNM), A. Gulati (U. Sydney), A. J. van der Horst (GWU), on behalf of the PanRadio GRB collaboration\n\nThe Australia Telescope Compact Array (ATCA) performed rapid-response observations of GRB 240421B (Williams et al., GCN 36208) at 5.5, 9, 16.7 and 21.2 GHz as part of the Long-term ATCA \"PanRadio GRB\" follow-up programme C3542 (PI. Anderson). ATCA observed from 2024-04-21 17:00 UT (7.3 hours post-burst) to 2024-04-22 01:40 UT. In our preliminary analysis, we find no radio source coincident with the enhanced XRT position (Beardmore et al., GCN 36213) with 3 sigma upper limits of 57, 54, 60, 90 microJy/beam at 5.5, 9.0, 16.7 and 21.2 GHz, respectively.\n\nWe thank the CSIRO Space and Astronomy staff for supporting these observations. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility\n(https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36249.",
"published": "2024-04-23T09:50:29.673718Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T09:50:29.673731Z",
"modified": "2024-04-23T09:50:29.682672Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6867,
"topic": "gcn.circular",
"uuid": "02ccdf74-d540-49c3-905f-6bc9b16a5cfa",
"title": "GRB 240419A: Possible ATCA radio detection",
"submitter": "Hop gcn.circular",
"authors": "Gemma Anderson at Curtin U <gemma.anderson@curtin.edu.au>",
"data": {
"date": "24/04/23 09:51:22 GMT",
"from": "Gemma Anderson at Curtin U <gemma.anderson@curtin.edu.au>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36250"
},
"title": "GCN CIRCULAR",
"number": "36250",
"subject": "GRB 240419A: Possible ATCA radio detection"
},
"message_text": "S. Chastain (UNM), G. E. Anderson (Curtin University), J. K. Leung (U. Toronto/HUJI), L. Rhodes (U. Oxford), S. D. Ryder (Macquarie), A. Gulati (U. Sydney), A. J. van der Horst (GWU), on behalf of the PanRadio GRB collaboration\n\nThe Australia Telescope Compact Array (ATCA) performed rapid follow-up observations of GRB 240419A (Siegel et al., GCN 36169) at 5.5, 9, and 18 GHz as part of the Long-term ATCA \"PanRadio GRB\" follow-up programme C3542 (PI. Anderson). ATCA began observing at 2024-04-19 04:00 UT (2.2 hours post-burst) up until 12:30 UT. In our preliminary analysis, we have a marginal detect of 63 +/- 18 microJy/beam at 18 GHz that is coincident with the enhanced XRT position (Goad et al., GCN 36174). We obtain 3 sigma upper limits of 39 and 42 microJy/beam at 5.5 and 9.0, respectively. Further observations are planned.\n\nWe thank the CSIRO Space and Astronomy staff for supporting these observations. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility\n(https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36250.",
"published": "2024-04-23T09:51:29.738709Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T09:51:29.738724Z",
"modified": "2024-04-23T09:51:29.745496Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6873,
"topic": "gcn.circular",
"uuid": "d7b7c4d0-05fb-4376-b3c1-ec730ddb8f1e",
"title": "LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations",
"submitter": "Hop gcn.circular",
"authors": "S. Srivastav at Oxford <shubhamsrivastav@gmail.com>",
"data": {
"date": "24/04/23 11:29:53 GMT",
"from": "S. Srivastav at Oxford <shubhamsrivastav@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36251"
},
"title": "GCN CIRCULAR",
"number": "36251",
"subject": "LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations"
},
"message_text": "S. Srivastav (Oxford), S. J. Smartt (QUB/Oxford), K. W. Smith, D. R. Young, M. Nicholl, M. D. Fulton, T. Moore, A. Aamer, C. R. Angus, M. McCollum, S. Sim, J. Weston, X. Sheng (QUB), L. Shingles (GSI/QUB), J. Sommer (LMU/QUB), J. Gillanders, H. Stevance, L. Rhodes, A. Andersson (Oxford), L. Denneau, J. Tonry, H. Weiland, A. Lawrence, R. Siverd (IfA, University of Hawaii), N. Erasmus, W. Koorts (South African Astronomical Observatory), J. Anderson (ESO), A. Jordan, V. Suc (UAI, Obstech) A. Rest (STScI), T.-W. Chen (NCU), C. Stubbs (Harvard):\n\nWe report observations of the skymap of the NSBH/BNS merger event S240422ed (The LIGO-Virgo-Kagra Collaboration, GCN 36236) with the ATLAS survey (Tonry et al., 2018, PASP, 13, 164505). ATLAS is a quadruple 0.5m optical telescope survey system (Hawaii, South Africa, Chile) employing two filters, cyan and orange. In our primary NASA mission for Near-Earth Object discovery, we cover the entire visible night sky every 24 hrs to magnitude depths m ~ 19.5, weather and Moon permitting.\n\nWe targeted the accessible skymap of S240422ed with a sequence of quads (4 x 110 s images) obtained at each pointing position. Data acquisition began at MJD 60422.9653 or 2024-04-22 23:10:01.920 (UTC), 0.8 hrs after the LVC initial alert and 1.6 hrs after the merger event. The images were processed with the ATLAS pipeline, and reference images were subtracted. Transient candidates were identified and run through our standard filtering procedures (Smith et al., 2020, PASP, 132, 1). We covered 242 square degrees of the bilby.fits skymap 90% area, and covered a sky region totalling 77% of the event's full localisation likelihood.\n\nObservations lasted between ~1.6 hrs to 7.2 hrs after the NSBH/BNS merger. We found no plausible new transient sources that had not been previously detected by ATLAS before the merger event or reported to the IAU Transient name server. The 5-sigma depths of our images were typically 18.7 < m_o < 19.5 AB mag. We are reporting all discoveries to the TNS, where they can be tracked, classified, searched, and commented upon. We encourage further information to be reported on the TNS object pages.\n\nThe Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for Near-Earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen's University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36251.",
"published": "2024-04-23T11:30:12.536570Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T11:30:12.536585Z",
"modified": "2024-04-23T11:30:12.543199Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6876,
"topic": "gcn.circular",
"uuid": "2d8db7e9-6773-4c81-a40b-c4ba967a1e82",
"title": "GRB 240418A: Swift-BAT refined analysis",
"submitter": "Hop gcn.circular",
"authors": "Mike Moss at NASA GSFC <mikejmoss3@gmail.com>",
"data": {
"date": "24/04/23 12:59:27 GMT",
"from": "Mike Moss at NASA GSFC <mikejmoss3@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36254"
},
"title": "GCN CIRCULAR",
"number": "36254",
"subject": "GRB 240418A: Swift-BAT refined analysis"
},
"message_text": "D. M. Palmer (LANL), S. D. Barthelmy (GSFC),\nH. A. Krimm (NSF), S. Laha (GSFC/UMBC),\nA. Y. Lien (U Tampa), C. B. Markwardt (GSFC),\nM. J. Moss (GSFC), T. Parsotan (GSFC),\nT. Sakamoto (AGU), M. H. Siegel (PSU)\n(i.e. the Swift-BAT team):\n\nUsing the data set from T-60 to T+243 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 240418A (trigger #1222885)\n(Siegel, et al., GCN Circ. 36162). The BAT ground-calculated position is\nRA, Dec = 239.342, 23.632 deg which is\n RA(J2000) = 15h 57m 22.0s\n Dec(J2000) = +23d 37' 54.4\"\nwith an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 79%.\n\nThe mask-weighted light curve shows a single, dim pulse peaking at T0+5 s.\nThe T90 (15-350 keV) is 12.00 +- 3.61 sec (estimated error including systematics).\n\nThe time-averaged spectrum from T-0.47 to T+12.53 sec is best fit by a simple\npower-law model. The power law index of the time-averaged spectrum is\n1.99 +- 0.31. The fluence in the 15-150 keV band is 2.3 +- 0.5 x 10^-07 erg/cm2.\nThe 1-sec peak photon flux measured from T+4.53 sec in the 15-150 keV band\nis 0.5 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence\nlevel.\n\nThe results of the batgrbproduct analysis are available at\nhttps://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1222885\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36254.",
"published": "2024-04-23T12:59:38.231470Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T12:59:38.231482Z",
"modified": "2024-04-23T12:59:38.241106Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6877,
"topic": "gcn.circular",
"uuid": "9ed430a5-f3ab-44d1-8f3e-4da64f7c73cb",
"title": "GRB 240419A: Swift-BAT refined analysis",
"submitter": "Hop gcn.circular",
"authors": "Mike Moss at NASA GSFC <mikejmoss3@gmail.com>",
"data": {
"date": "24/04/23 13:00:27 GMT",
"from": "Mike Moss at NASA GSFC <mikejmoss3@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36255"
},
"title": "GCN CIRCULAR",
"number": "36255",
"subject": "GRB 240419A: Swift-BAT refined analysis"
},
"message_text": "T. Parsotan (GSFC), S. D. Barthelmy (GSFC),\nH. A. Krimm (NSF), S. Laha (GSFC/UMBC),\nA. Y. Lien (U Tampa), C. B. Markwardt (GSFC),\nM. J. Moss (GSFC), D. M. Palmer (LANL),\nT. Sakamoto (AGU), M. H. Siegel (PSU)\n(i.e. the Swift-BAT team):\n\nUsing the data set from T-60 to T+243 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 240419A (trigger #1222955)\n(Siegel, et al., GCN Circ. 36169). The BAT ground-calculated position is\nRA, Dec = 94.505, -44.964 deg which is\n RA(J2000) = 06h 18m 01.3s\n Dec(J2000) = -44d 57' 50.2\"\nwith an uncertainty of 3.0 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 89%.\n\nThe mask-weighted light curve shows two dim pulses at T0-7 s and T0+0 s,\nrespectively.\nThe T90 (15-350 keV) is 3.00 +- 1.41 sec (estimated error including systematics).\n\nThe time-averaged spectrum from T-0.43 to T+2.57 sec is best fit by a simple\npower-law model. The power law index of the time-averaged spectrum is\n1.71 +- 0.38. The fluence in the 15-150 keV band is 8.4 +- 2.1 x 10^-08 erg/cm2.\nThe 1-sec peak photon flux measured from T+0.57 sec in the 15-150 keV band\nis 0.6 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence\nlevel.\n\nThe results of the batgrbproduct analysis are available at\nhttps://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1222955\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36255.",
"published": "2024-04-23T13:00:34.298381Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T13:00:34.298396Z",
"modified": "2024-04-23T13:00:34.304325Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6960,
"topic": "gcn.circular",
"uuid": "20111cfe-4e55-4f17-b70c-532f224af843",
"title": "LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate",
"submitter": "Hop gcn.circular",
"authors": "Akash Maurya at International Centre for Theoretical Sciences (ICTS) <akash.maurya@icts.res.in>",
"data": {
"date": "24/04/26 03:51:46 GMT",
"from": "Akash Maurya at International Centre for Theoretical Sciences (ICTS) <akash.maurya@icts.res.in>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36312"
},
"title": "GCN CIRCULAR",
"number": "36312",
"subject": "LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate"
},
"message_text": "The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:\n\nWe identified the compact binary merger candidate S240426s during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2024-04-26 03:14:51.975 UTC (GPS time: 1398136509.975). The candidate was found by the CWB [1], GstLAL [2], MBTA [3], and PyCBC Live [4] analysis pipelines.\n\nS240426s is an event of interest because its false alarm rate, as estimated by the online analysis, is 7.6e-09 Hz, or about one in 4 years. The event's properties can be found at this URL:\n\nhttps://gracedb.ligo.org/superevents/S240426s\n\nAfter parameter estimation by RapidPE-RIFT [5], the classification of the GW signal, in order of descending probability, is BBH (98%), Terrestrial (2%), NSBH (<1%), or BNS (<1%).\n\nAssuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [6] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [6] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 3%.\n\nTwo sky maps are available at this time and can be retrieved from the GraceDB event page:\n * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [7], distributed via GCN notice about 33 seconds after the candidate event time.\n * bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [7], distributed via GCN notice about 5 minutes after the candidate event time.\n\nThe preferred sky map at this time is bayestar.multiorder.fits,2. For the bayestar.multiorder.fits,2 sky map, the 90% credible region is 4389 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 454 +/- 143 Mpc (a posteriori mean +/- standard deviation).\n\nFor further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/.\n\n [1] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004\n [2] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625\n [3] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913\n [4] Dal Canton et al. ApJ 923, 254 (2021) doi:10.1088/1361-6382/abe913\n [5] Rose et al. (2022) arXiv:2201.05263 and Pankow et al. PRD 92, 023002 (2015) doi:10.1103/PhysRevD.92.023002\n [6] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe\n [7] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36312.",
"published": "2024-04-26T03:52:03.788187Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-26T03:52:03.788204Z",
"modified": "2024-04-26T03:52:03.794250Z",
"nonlocalizedevents": [
{
"event_id": "S240426s"
}
],
"targets": []
},
{
"id": 6879,
"topic": "gcn.circular",
"uuid": "bb2e1099-bdc5-4966-8ede-6b3f2ed24f4d",
"title": "LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations",
"submitter": "Hop gcn.circular",
"authors": "Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra@roma2.infn.it>",
"data": {
"date": "24/04/23 14:44:02 GMT",
"from": "Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra@roma2.infn.it>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36256"
},
"title": "GCN CIRCULAR",
"number": "36256",
"subject": "LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations"
},
"message_text": "Rosa L. Becerra (UTOV), Alan M. Watson (UNAM), Simone Dichiara (PSU), Eleonora Troja (UTOV), Nat Butler (ASU), William H. Lee (UNAM), Alexander Kutyrev (GSFC/UMD), Tsvetelina Dimitrova (ASU), Keneth Garcia Cifuentes (UNAM), Camila Angulo Valdez (UNAM), Margarita Pereyra (UNAM) and Océlotl Lopez (UNAM) report:\n\nWe observed LIGO/Virgo/KAGRA S240422ed (GCN #36236) with the DDOTI/OAN wide-field imager at the Observatorio Astronomico Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of 2024-04-23 UTC.\n\nWe tiled the LVK localization with two pointings covering about 104 square degrees and including about 42% of the probability in the current BAYESTAR map. \n\nWe observed from 2024-04-23 03:15 UTC to 2024-04-23 05:04 UTC (from T+5.7 to\nT+7.5 hours after the event) obtaining a total of 54 minutes of exposure across the fields in the w filter, with 10-sigma limiting magnitudes of w~19 and constrained by the horizon.\n\nComparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogs we\ndetect no uncatalogued sources within the observed field to our 10-sigma\nlimit. \n\nFurther observations are planned.\n\nWe thank the staff of the Observatorio Astronomico Nacional in San Pedro\nMartir.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36256.",
"published": "2024-04-23T14:44:17.402779Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T14:44:17.402802Z",
"modified": "2024-04-23T14:44:17.409852Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6880,
"topic": "gcn.circular",
"uuid": "9184d024-bca2-45b0-b247-fc7d9eedc736",
"title": "LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search",
"submitter": "Hop gcn.circular",
"authors": "kendall.ackley@warwick.ac.uk",
"data": {
"date": "24/04/23 16:55:56 GMT",
"from": "kendall.ackley@warwick.ac.uk",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36257"
},
"title": "GCN CIRCULAR",
"number": "36257",
"subject": "LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search"
},
"message_text": "K. Ackley, M. J. Dyer, J. Lyman, D. O'Neill, K. Ulaczyk; F. Jimenez-Ibarra, A. Kumar, B. Godson, T. Killestein, B. Gompertz, M. Kennedy, S. Belkin, J. Rana, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall; E. Palle and D. Pollacco report on behalf of the GOTO collaboration:\n\nWe report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to the LIGO/Virgo/KAGRA candidate NSBH event S240422ed (The LIGO-Virgo-KAGRA Collaboration, GCN 36236). Targeted observations covering 260 sqr. degrees or 96.2% of the localisation probability of the Bilby skymap (The LIGO-Virgo-KAGRA Collaboration, GCN 36240) were performed between 21:38 UT and 23:09 UT April 22 2024 (starting 2.7 minutes after trigger) with GOTO-N and 08:33 UT and 12:47 UT on April 23 2024 (starting 10.96 hours after trigger) with GOTO-S.\n\nExposures were taken in L-band (400-700 nm passband) and the median 5 sigma depth was L = 18.84 AB magnitudes with GOTO-N and 19.56 with GOTO-S, under bright moon and partly cloudy conditions. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and not corrected for Galactic extinction.\n\nImages were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using recent survey observations of the same pointings. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogs. Human vetting was carried out in real time on any candidates that passed the above checks. After filtering for image quality, the total vetted region covered 45% of the skymap probability.\n\nNo significant counterpart sources that can be associated with S240422ed have been identified so far, consistent with reports from other search efforts.\n\nObservations are ongoing and any notable candidates will be reported via TNS and GCN.\n\nGOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36257.",
"published": "2024-04-23T16:56:13.515664Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T16:56:13.515682Z",
"modified": "2024-04-23T16:56:13.524619Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6881,
"topic": "gcn.circular",
"uuid": "bbce1625-3fc1-4633-8463-a4684ea372b2",
"title": "LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap",
"submitter": "Hop gcn.circular",
"authors": "Ken Smith at Queen's University Belfast <k.w.smith@qub.ac.uk>",
"data": {
"date": "24/04/23 16:56:02 GMT",
"from": "Ken Smith at Queen's University Belfast <k.w.smith@qub.ac.uk>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36258"
},
"title": "GCN CIRCULAR",
"number": "36258",
"subject": "LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap"
},
"message_text": "K. W. Smith (QUB), M. Huber (IfA, Hawaii), S. Srivastav (Oxford), S. J. Smartt (Oxford/QUB), K. C. Chambers, (IfA, Hawaii), D. R. Young, M. Nicholl, M. D. Fulton, A. Aamer, C. R. Angus, M. McCollum, T. Moore, S. Sim, J. Weston, X. Sheng (QUB), P. Ramsden (QUB/Birmingham), L. Shingles (GSI/QUB), J. Sommer (LMU/QUB), J. Gillanders, H. Stevance, L. Rhodes, A. Andersson (Oxford), A. S. B. Schultz, T. de Boer, J. Herman, J. Fairlamb, H. Gao, C. C. Lin, T. Lowe, E. Magnier, P. Minguez, I. A. Smith, R. J. Wainscoat (IfA, Univ. Hawaii), T.-W. Chen (TUM), A. Rest (STScI), C. Stubbs (Harvard):\n\nWe report observations of the Bilby.fits skymap of the NSBH merger event S240422ed (The LIGO-Virgo-Kagra Collaboration, GCN 36236) with the Pan-STARRS telescope system (Chambers et al., 2016, ArXiv e-prints, 1612.05560). The Pan-STARRS system comprises of two 1.8m telescope units located at the summit of Haleakala on the Hawaiian island of Maui, employing an SDSS-like filter system denoted as grizy, and a broad w-filter, which is a composite of the gri-filters. In our primary NASA mission for Near-Earth Object discovery, we scan the visible night sky North of -50 degrees declination to magnitude depths m~22, weather and Moon permitting. \n\nDuring focused science operations, we covered part of the accessible skymap of S240422ed. Tiling sequences of multiple 45-sec images were taken at each pointing position. Pan-STARRS1 was used with the i-band filter and Pan-STARRS2 with the z-band filter. We observed with a wedding cake strategy, with more exposures in the high probability regions and stacked the 45 second frames leading to a spatially varying sensitivity (the most sensitive regions being correlated with the highest probability density). The images were processed with the Pan-STARRS pipeline. After astrometric and photometric calibration, reference images were subtracted from the target stacked images (Magnier et al., 2020a, ApJS, 251, 3; Magnier et al., 2020b, ApJS, 251, 6; Waters et al., 2020, ApJS, 251, 4). Transient candidates were identified and run through our standard filtering procedures, including rejection of artifacts with machine learning tools and cross-matching with galaxy, stellar and solar-system catalogs (e.g. Smith et al., 2020, PASP, 132, 1).\n\nWe covered 167 square degrees of the bilby.fits skymap 90% area, and covered a sky region totalling 65% of the event's full localisation. We covered nearly all the 90% region above declination -30 degrees, due to lack of reference frames below that declination. Data acquisition began at MJD 60423.24267554 or 2024-04-23 05:49:27 (UTC), 8.2 hrs after the merger event (which was 60422.89946078). The last image was taken at 60423.32659085. \n\nWe found no new transient sources that had not been previously detected by Pan-STARRS before the merger event or reported to the IAU Transient name server by another survey. The depths of these stacked images were typically i < 19.9 +/- 0.4 , z < 19.5 +/- 0.3. Any transients we do find during further processing will be reported to the TNS, where they can be tracked, classified, searched, and commented upon. We encourage further information to be reported on the TNS object pages. \n\nThe discoveries from this program are a byproduct of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) NEO survey observations. Operation of the Pan-STARRS1 and Pan-STARRS2 telescopes is primarily supported by the National Aeronautics and Space Administration under Grant No. NNX12AR65G and Grant No. NNX14AM74G issued through the SSO Near-Earth Object Observations Program. Data are processed at Queen's University Belfast and are enabled through the STFC grants to Oxford and QUB : ST/Y001605/1, ST/T000198/1, ST/X001253/1. \n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36258.",
"published": "2024-04-23T16:56:13.547293Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T16:56:13.547305Z",
"modified": "2024-04-23T16:56:13.553198Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6883,
"topic": "gcn.circular",
"uuid": "1caab1c4-70ee-4a57-a543-613bb18c7f08",
"title": "LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61",
"submitter": "Hop gcn.circular",
"authors": "Igor Andreoni at JSI/UMD/NASA <igor.andreoni@gmail.com>",
"data": {
"date": "24/04/23 18:11:21 GMT",
"from": "Igor Andreoni at JSI/UMD/NASA <igor.andreoni@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36259"
},
"title": "GCN CIRCULAR",
"number": "36259",
"subject": "LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61"
},
"message_text": "Lei Hu (CMU), Tomás Cabrera (CMU), Brendan O'Connor (CMU), Keerthi Kunnumkai (CMU), Igor Andreoni (UMD), Antonella Palmese (CMU) report on behalf of the GW-MMADS team:\n\n\nDuring GW-MMADS DECam follow-up (Palmese et al., GCN 36245) of the LIGO/Virgo/KAGRA event S240422ed (GCN 36236, GCN 36240), we serendipitously observed the location of the Swift/XRT source 61 (here labelled S240422ed_X61) at coordinates RA, Dec = 120.3245d, -28.1765d (J2000; [1]).\n\nIn our difference imaging relative to archival DECam images, obtained using SFFT (Hu et al., 2021), we do not detect any optical transient or variable emission within a 20 arcsec radius. Upper limits are reported below.\n\nfilter | observation time UT | limiting magnitude (AB, 5 sigma)\nDECam-r | 2024-04-22T23:59:29 | 22.46\nDECam-z | 2024-04-23T02:55:26 | 21.33\n\n\n[1] https://gcn.gsfc.nasa.gov/other/S240422ed.counterpart\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36259.",
"published": "2024-04-23T18:11:37.705387Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T18:11:37.705408Z",
"modified": "2024-04-23T18:11:37.713887Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6884,
"topic": "gcn.circular",
"uuid": "1d0ac006-52d9-44af-869b-4eeedd94a06b",
"title": "LIGO/Virgo/KAGRA S240421ar: Updated Sky localization",
"submitter": "Hop gcn.circular",
"authors": "Elise Sänger at Max Planck Institute for Gravitational Physics (AEI Potsdam) <elise.sanger@ligo.org>",
"data": {
"date": "24/04/23 18:41:46 GMT",
"from": "Elise Sänger at Max Planck Institute for Gravitational Physics (AEI Potsdam) <elise.sanger@ligo.org>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36260"
},
"title": "GCN CIRCULAR",
"number": "36260",
"subject": "LIGO/Virgo/KAGRA S240421ar: Updated Sky localization"
},
"message_text": "The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:\n\nWe have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S240421ar (GCN Circular 36205). This candidate from a weakly modeled CBC search was previously erroneously referred to as \"unmodeled transient\". Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline0.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:\n\nhttps://gracedb.ligo.org/superevents/S240421ar\n\nFor the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is 2601 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 7702 +/- 2899 Mpc (a posteriori mean +/- standard deviation).\n\nFor further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/.\n\n [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36260.",
"published": "2024-04-23T18:42:04.647313Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T18:42:04.647328Z",
"modified": "2024-04-23T18:42:04.654041Z",
"nonlocalizedevents": [
{
"event_id": "S240421a"
}
],
"targets": []
},
{
"id": 6885,
"topic": "gcn.circular",
"uuid": "99809719-afed-4984-8a35-f794c579ae42",
"title": "IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube",
"submitter": "Hop gcn.circular",
"authors": "Sam Hori at IceCube/U Wisc-Madison <sahori@wisc.edu>",
"data": {
"date": "24/04/23 18:50:37 GMT",
"from": "Sam Hori at IceCube/U Wisc-Madison <sahori@wisc.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36261"
},
"title": "GCN CIRCULAR",
"number": "36261",
"subject": "IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube"
},
"message_text": "The IceCube Collaboration (http://icecube.wisc.edu/) reports:\n\n\nIceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-240419A (https://gcn.nasa.gov/circulars/36195 ) in a time range of 1000 seconds centered on the alert event time (2024-04-19 23:17:21.040 UTC to 2024-04-19 23:34:01.040 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-240419A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-240419A ranges from 1.4e-01 to 1.5e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 3e+02 GeV and 2e+05 GeV.\n\n\nA subsequent search was performed including 2 days of data centered on the alert event time (2024-04-18 23:25:41.040 UTC to 2024-04-20 23:25:41.040 UTC). In this case, we report a p-value of 0.34, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90%spatial containment region of IceCube-240419A is 1.6e-01 GeV cm^-2 in a 2 day time window.\n\n\nThe IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu<mailto:roc@icecube.wisc.edu>.\n\n\n[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36261.",
"published": "2024-04-23T18:50:54.669253Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T18:50:54.669264Z",
"modified": "2024-04-23T18:50:54.675826Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6886,
"topic": "gcn.circular",
"uuid": "9b92b364-2b5b-41f1-9728-6cbf56d5c785",
"title": "LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61",
"submitter": "Hop gcn.circular",
"authors": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"data": {
"date": "24/04/23 19:01:55 GMT",
"from": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36262"
},
"title": "GCN CIRCULAR",
"number": "36262",
"subject": "LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61"
},
"message_text": "Viraj Karambelkar (Caltech), Geoffrey Mo (MIT), Robert Stein (Caltech),\nNathan Lourie (MIT), Danielle Frostig (MIT), Tomas Ahumada (Caltech),\nRobert Simcoe (MIT), and Mansi Kasliwal (Caltech)\n\nDuring WINTER follow-up observations (GCN 36248) of the LVK event S240422ed\n(GCN 36236, GCN 36240), we observed the location of the Swift/XRT source 61\n(labeled as S240422ed_X61) at coordinates RA, Dec = 120.3245, -28.1765 (\nhttps://gcn.gsfc.nasa.gov/other/S240422ed.counterpart) in the near-infrared\nJ-band. Our observations of this field began at UTC 2024-04-23T03:13:34 and\nlasted for 480 seconds.\n\nThere are no archival J-band images of this field, so we compare the WINTER\nimage to a y-band image from the PS1 survey (https://ps1images.stsci.edu/).\nWe do not detect any new source within 20 arcsec of the Swift X-ray source,\nto a 5-sigma depth of 16.6 mag (AB). This estimate is not corrected for\nGalactic line-of-sight extinction (integrated E(B-V) = 0.7 mag\ncorresponding to total A_J = 0.5 mag) along this direction.\n\nWINTER (Wide-field INfrared Transient ExploreR) is a partnership between\nMIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF\nAAG, the David and Lucille Packard Foundation, and the MIT Kavli Institute\nfor Astrophysics and Space Research.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36262.",
"published": "2024-04-23T19:02:05.801107Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T19:02:05.801119Z",
"modified": "2024-04-23T19:02:05.808155Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6887,
"topic": "gcn.circular",
"uuid": "bf07e376-64ae-4c06-adec-d0c440a92ef6",
"title": "LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search",
"submitter": "Hop gcn.circular",
"authors": "Harsh Kumar at Center for Astrophysics | Harvard & Smithsonian <harshkosli13@gmail.com>",
"data": {
"date": "24/04/23 20:04:38 GMT",
"from": "Harsh Kumar at Center for Astrophysics | Harvard & Smithsonian <harshkosli13@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36263"
},
"title": "GCN CIRCULAR",
"number": "36263",
"subject": "LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search"
},
"message_text": "H. Kumar, D. Hiramatsu, E. Berger, A. Villar, K. D. Soto, S. K. Yadavalli, M. Hussaini, A. Gagliano, C. Ransome (Harvard) report:\n\n\nWe used the LDSS-3 imager on the 6.5m Magellan Clay telescope to carry out a search for an optical counterpart to the gravitational wave event S240422ed (GCN #36236). A series of 120-second i-band images were obtained starting about 5 hours after the trigger, targeting galaxies coincident with the 3D localization of the event as described by Piro et al. (GCN #36244).\n\nInspecting the images in the vicinity of galaxies within the localization volume, in comparison to PS1/3pi images, we identify two sources (one low significance):\n\n------------------------------------------------------------------\nRA (J2000) | Dec (J2000)| Filter | Mag(AB)| Remarks\n------------------------------------------------------------------\n07:57:41.422 | -21:53:15.12 | i | ~21.5 | S/N ~ 8\n08:06:04.799 | -22:27:03.71 | i | ~21.7 | S/N < 5\n------------------------------------------------------------------\n\nThese sources are slightly fainter than the reference images from PS1/3pi, and we therefore cannot comment about their transient nature. There are no minor planets around these coordinates. Further observations of these candidates are planned, and we encourage additional follow-up.\n\nWe thank Marcelo Mora, Povilas Palunas, and the LCO staff for rapid execution of these observations.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36263.",
"published": "2024-04-23T20:04:59.854317Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T20:04:59.854332Z",
"modified": "2024-04-23T20:04:59.864045Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6888,
"topic": "gcn.circular",
"uuid": "220a46ed-981e-47c4-b726-26ee17a97668",
"title": "LIGO/Virgo/KAGRA S240422ed: LAST optical observations",
"submitter": "Hop gcn.circular",
"authors": "Simone Garrappa at DESY <simone.garrappa@desy.de>",
"data": {
"date": "24/04/23 20:12:14 GMT",
"from": "Simone Garrappa at DESY <simone.garrappa@desy.de>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36264"
},
"title": "GCN CIRCULAR",
"number": "36264",
"subject": "LIGO/Virgo/KAGRA S240422ed: LAST optical observations"
},
"message_text": "R. Konno (WIS), S. Garrappa (WIS), E. O. Ofek (WIS), S. Ben-Ami (WIS), David Polishook (WIS) on behalf of the LAST collaboration:\n\nWe report observations of the Bilby.fits skymap of the NSBH merger event S240422ed (GCN 36236) with the Large Array Survey Telescope (LAST; Ofek et al. 2023 PASP 135, 5001; Ben-Ami et al. 2023 PAST 135, 5002).\nWe used 8 telescopes (out of 32 operational) with no filter (clear - similar to the GAIA Bp band)Â to cover 70%Â of the 90% confidence region of the event. A total of 11 fields were observed, each for a total of 40x20 seconds integration.\nThe fields were observed at an airmass of about 2.0, with the full Moon at about 78 deg distance. Under these conditions, the limiting magnitude reported by the LAST pipeline (Ofek et al. 2023 PASP 135, 4502) in 20x20 s exposures is about 18.5.\nNo reference images are available for these fields.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36264.",
"published": "2024-04-23T20:12:28.717708Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T20:12:28.717727Z",
"modified": "2024-04-23T20:12:28.724164Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6890,
"topic": "gcn.circular",
"uuid": "75584e59-21e5-48b3-a9c7-173a178aeebe",
"title": "LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration",
"submitter": "Hop gcn.circular",
"authors": "Tomoki Morokuma at Chiba Institute of Technology <tomoki.morokuma@p.chibakoudai.jp>",
"data": {
"date": "24/04/23 23:59:24 GMT",
"from": "Tomoki Morokuma at Chiba Institute of Technology <tomoki.morokuma@p.chibakoudai.jp>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36265"
},
"title": "GCN CIRCULAR",
"number": "36265",
"subject": "LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration"
},
"message_text": "Tomoki Morokuma (ARC/Chitech), Nozomu Tominaga, Ichi Tanaka, and Michitoshi Yoshida (NAOJ) report on behalf of Japanese Collaboration for Gravitational-Wave Electro-Magnetic Follow-up (J-GEM) collaboration:\n\nWe conducted near-infrared imaging observations of galaxies in the localization region of the gravitational wave event LIGO/Virgo/KAGRA S240422ed (GCN 36236) using the Multi-Object InfraRed Camera and Spectrograph (MOIRCS; 3.9x6.9 arcmin field-of-view; Suzuki, R. et al. 2008, PASJ, 60, 1347; Ichikawa, T. et al. 2006, SPIE, 6269, 38) on the 8.2-m Subaru telescope. We started our observations at UT 2024-04-23 05:21, about 7.8 hours after the event.\n\nWe observed 100 galaxies in total in Y and Ks bands with 15-32 sec exposures. The target galaxies are selected from the list of potential host galaxies for this event (Dalya, G. et al. 2019, GCN, 24171) around the central coordinate of the localization. The list of the galaxies we observed is shown in the table below. The data were reduced with the MCSRED (Tanaka, I. et al. 2011, PASJ, 63, S415) and detailed examination of the obtained data is now underway.\n\nObserved galaxies\nGL075344-262712 07:53:43.70 -26:27:11.52\nGL075620-312150 07:56:19.68 -31:21:49.68\nGL075851-343144 07:58:51.24 -34:31:44.04\nGL075925-273216 07:59:25.05 -27:32:16.44\nGL080201-305049 08:02:00.74 -30:50:48.84\nGL080236-340407 08:02:35.52 -34:04:07.32\nGL080242-314115 08:02:42.28 -31:41:15.00\nGL080305-261201 08:03:05.16 -26:12:00.72\nGL080334-330027 08:03:34.20 -33:00:26.64\nGL080339-330139 08:03:38.56 -33:01:38.64\nGL080436-250927 08:04:35.59 -25:09:27.00\nGL080442-265813 08:04:41.68 -26:58:13.08\nGL080501-324313 08:05:01.15 -32:43:13.08\nGL080522-322313 08:05:22.39 -32:23:12.84\nGL080528-315445 08:05:28.27 -31:54:45.00\nGL080542-315238 08:05:42.48 -31:52:37.92\nGL080550-261139 08:05:50.18 -26:11:39.12\nGL080551-255848 08:05:50.71 -25:58:48.00\nGL080556-303009 08:05:55.60 -30:30:09.36\nGL080620-312607 08:06:20.18 -31:26:07.44\nGL080633-300736 08:06:32.59 -30:07:35.76\nGL080702-314302 08:07:01.70 -31:43:02.28\nGL080708-290851 08:07:07.89 -29:08:51.36\nGL080724-264036 08:07:23.56 -26:40:36.48\nGL080726-292734 08:07:25.84 -29:27:34.56\nGL080747-275243 08:07:47.13 -27:52:43.32\nGL080749-255717 08:07:49.44 -25:57:17.28\nGL080750-290734 08:07:49.75 -29:07:34.32\nGL080826-310301 08:08:25.68 -31:03:00.72\nGL080850-243120 08:08:49.87 -24:31:20.28\nGL080855-300836 08:08:54.60 -30:08:36.24\nGL080855-301552 08:08:55.36 -30:15:52.56\nGL080903-242702 08:09:02.54 -24:27:02.16\nGL080906-270633 08:09:06.31 -27:06:33.12\nGL080926-240558 08:09:25.70 -24:05:58.20\nGL081042-304908 08:10:41.85 -30:49:07.68\nGL081051-330116 08:10:51.14 -33:01:15.60\nGL081055-305129 08:10:55.03 -30:51:28.80\nGL081106-305231 08:11:05.59 -30:52:30.72\nGL081106-234121 08:11:06.02 -23:41:21.12\nGL081116-305424 08:11:16.39 -30:54:23.76\nGL081119-254058 08:11:19.27 -25:40:58.44\nGL081123-321104 08:11:23.25 -32:11:04.20\nGL081135-321943 08:11:35.04 -32:19:42.96\nGL081155-235315 08:11:54.76 -23:53:14.64\nGL081221-244709 08:12:20.61 -24:47:08.88\nGL081235-203457 08:12:34.65 -20:34:57.00\nGL081239-315224 08:12:38.66 -31:52:24.24\nGL081240-312406 08:12:39.50 -31:24:06.12\nGL081248-313414 08:12:48.16 -31:34:14.16\nGL081301-285304 08:13:00.96 -28:53:03.48\nGL081312-280235 08:13:11.52 -28:02:34.44\nGL081338-205947 08:13:37.75 -20:59:47.04\nGL081352-290731 08:13:51.67 -29:07:31.08\nGL081403-341622 08:14:03.26 -34:16:21.72\nGL081413-332820 08:14:13.00 -33:28:19.92\nGL081419-322317 08:14:19.10 -32:23:16.80\nGL081425-322500 08:14:24.79 -32:25:00.12\nGL081435-234301 08:14:35.49 -23:43:00.84\nGL081450-224615 08:14:50.18 -22:46:14.88\nGL081452-292944 08:14:51.50 -29:29:44.16\nGL081502-331829 08:15:01.77 -33:18:28.80\nGL081502-225349 08:15:02.01 -22:53:48.84\nGL081514-235249 08:15:13.89 -23:52:49.08\nGL081521-330708 08:15:21.04 -33:07:08.04\nGL081529-304751 08:15:29.25 -30:47:51.00\nGL081547-283019 08:15:47.13 -28:30:19.08\nGL081549-233224 08:15:48.52 -23:32:23.64\nGL081551-224821 08:15:50.52 -22:48:20.88\nGL081600-225336 08:16:00.36 -22:53:35.88\nGL081608-315204 08:16:08.20 -31:52:04.44\nGL081614-213024 08:16:13.53 -21:30:23.76\nGL081628-274822 08:16:28.05 -27:48:22.32\nGL081634-203944 08:16:33.60 -20:39:43.92\nGL081638-245039 08:16:38.16 -24:50:39.48\nGL081645-203612 08:16:45.48 -20:36:11.88\nGL081658-255212 08:16:58.29 -25:52:12.00\nGL081703-234745 08:17:02.66 -23:47:44.52\nGL081737-311300 08:17:36.91 -31:13:00.12\nGL081751-260634 08:17:51.19 -26:06:34.56\nGL081806-200632 08:18:05.80 -20:06:32.04\nGL081854-324543 08:18:54.19 -32:45:43.20\nGL081855-301427 08:18:55.36 -30:14:27.24\nGL081859-231650 08:18:58.68 -23:16:50.52\nGL081904-370400 08:19:03.60 -37:03:59.40\nGL081914-284340 08:19:14.23 -28:43:40.08\nGL081951-224338 08:19:51.12 -22:43:38.28\nGL082052-281358 08:20:51.55 -28:13:58.08\nGL082119-292224 08:21:18.96 -29:22:23.88\nGL082133-270940 08:21:33.14 -27:09:39.96\nGL082144-221105 08:21:43.51 -22:11:04.92\nGL082210-255316 08:22:10.44 -25:53:16.08\nGL082225-270438 08:22:25.44 -27:04:38.28\nGL082317-220507 08:23:16.58 -22:05:06.72\nGL082342-291616 08:23:42.26 -29:16:16.32\nGL082453-231312 08:24:53.01 -23:13:12.36\nGL082619-205052 08:26:19.20 -20:50:52.08\nGL082626-272137 08:26:26.16 -27:21:37.08\nGL082626-272138 08:26:26.42 -27:21:37.44\nGL082722-262347 08:27:21.67 -26:23:47.40\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36265.",
"published": "2024-04-23T23:59:45.585963Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-23T23:59:45.585983Z",
"modified": "2024-04-23T23:59:45.595925Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6892,
"topic": "gcn.circular",
"uuid": "0a7b54f4-542a-439a-a43f-8890801d4a57",
"title": "LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS",
"submitter": "Hop gcn.circular",
"authors": "Griffin Hosseinzadeh <griffin0@arizona.edu>",
"data": {
"date": "24/04/24 01:03:00 GMT",
"from": "Griffin Hosseinzadeh <griffin0@arizona.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36266"
},
"title": "GCN CIRCULAR",
"number": "36266",
"subject": "LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS"
},
"message_text": "Griffin Hosseinzadeh (UA), Manisha Shrestha (UA), Charles D. Kilpatrick (NU), Jillian C. Rastinejad (NU), Jeniveve Pearson (UA), Jennifer E. Andrews (Gemini), David J. Sand (UA), K. Azalee Bostroem (UA), Philip N. Daly (UA), Wen-fai Fong (NU), Michael J. Lundquist (Keck), Kerry Paterson (MPIA), Samuel D. Wyatt (GSFC), David Rankin (UA), Alexander R. Gibbs (UA), and D. Carson Fuls (UA) report:\n\nWe initiated observations of the localization region of S240422ed on 2024-04-23 03:22:01 UT using the 5 square degree imager mounted on the 1.5m Catalina Sky Survey (CSS) telescope on Mt. Lemmon, AZ. We observed 24 fields in the 95% confidence region of the initial Bayestar localization map (LVK Collaboration 2024, GCN 36236) that were accessible from southern Arizona, which cover approximately 23% of the cumulative probability according to the updated Bilby localization map (LVK Collaboration 2024, GCN 36240). We have reported our pointings to the Treasure Map (Wyatt et al. 2020; doi:10.5281/zenodo.1105274). The typical limiting magnitude of each CSS pointing was G~19.5 mag (calibrated to Gaia DR2).\n\nWe performed a real-time analysis of the observations. Following the methods outlined in Rastinejad et al. (2022), we crossmatch each candidate with the TNS (Gal-Yam 2021) and point source catalogs (Tachibana and Miller 2018; Jayasinghe et al. 2019; Flesch et al. 2021; Gaia Collaboration 2023), search public ZTF photometry (Bellm et al. 2019), and run ATLAS forced photometry (Shingles et al. 2021) at the position of the candidate to rule out transients unrelated to the GW event. We determine a most likely host galaxy using the probability of chance coincidence method (Bloom et al. 2002) and search for an associated spectroscopic or photometric redshift in public galaxy catalogs (White et al. 2011; Alam et al. 2015; Beck et al. 2016, 2021; Dalya et al. 2021; DESI Collaboration et al. 2023).\n\nWe do not find any credible candidates in our observations. Follow-up observations and further analysis are ongoing.\n\nSAGUARO stands for Searches After Gravitational-waves Using ARizona's Observatories (Hosseinzadeh et al. 2024). It is a partnership between the University of Arizona and Northwestern University.\n\n# References\n| source | citation |\n| ------------ | ---------------------- |\n| gcn_circular | 36236 |\n| gcn_circular | 36240 |\n| doi | 10.5281/zenodo.1105274 |\n\n\n\n This message was sent via HERMES. A machine readable version can be found at https://hermes.lco.global/message/b2fc6e3b-4989-47dc-a75c-e09fabfafaec\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36266.",
"published": "2024-04-24T01:03:19.827000Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T01:03:19.827020Z",
"modified": "2024-04-24T01:03:19.833571Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6893,
"topic": "gcn.circular",
"uuid": "ee45d9b9-2165-4e4e-b6aa-daa8c71fbbc1",
"title": "LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart",
"submitter": "Hop gcn.circular",
"authors": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"data": {
"date": "24/04/24 01:48:38 GMT",
"from": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36267"
},
"title": "GCN CIRCULAR",
"number": "36267",
"subject": "LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart"
},
"message_text": "A. L. Piro, J. D. Simon (Carnegie), A. Polin (Carnegie/Purdue), D. A. Coulter (STScI), M. R. Drout (Toronto), R. J. Foley, C. Rojas-Bravo (UC Santa Cruz), and C. D. Kilpatrick (Northwestern)\n\nreport on behalf of the Carnegie Gravitational wave ElectroMagnetic follow-up (CGEM) and the One-Meter Two-Hemisphere (1M2H) collaborations:\n\nAs part of our ongoing search for optical counterparts to the candidate gravitational wave event S240422ed (GCN 36236) using the 6.5m Magellan Clay telescope with the LDSS-3 imager (GCN 36244), we have detected an apparent transient source in an i-band image that is not present in archival Pan-STARRS images (Chambers et al., 2016). The transient is\n\nMag24a 07:56:05.6 -22:53:54 J2000\n\nWe have queried both the Minor Planet Checker and Transient Name Server, neither of which returned a known object.\n\nWe estimate the brightness of Mag24a is i = 23.3 mag at 20240423.98 UT. It is offset 2.1â west and 8.6â north from its apparent host galaxy, WISEA J075605.75-225400.0, which has a photometric redshift of z = 0.049 (Bilicki et al., 2014, ApJS, 210, 9), corresponding to 213 Mpc (i.e., within the current Bilby measured volume; GCN 36240). At this distance with a Milky Way extinction of A_i = 0.748 mag (Schlafly & Finkbeiner, 2011, ApJ, 737, 103) and no host-galaxy extinction, the absolute magnitude is M_i = -14.1 mag. At this distance, Mag24a is offset by 9.2 kpc from the assumed host galaxy in projection.\n\nWe are undertaking additional observations at this time, and encourage additional follow-up observations.\n\nWe thank Marcelo Mora, Povilas Palunas, and the rest of the LCO staff for making these observations possible.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36267.",
"published": "2024-04-24T01:48:58.639083Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T01:48:58.639098Z",
"modified": "2024-04-24T01:48:58.647696Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6896,
"topic": "gcn.circular",
"uuid": "184d6d9f-4d6b-43c4-9f76-33e1b8a3ec30",
"title": "IceCube Alert 240424.08: Global MASTER-Net observations report",
"submitter": "Hop gcn.circular",
"authors": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"data": {
"date": "24/04/24 02:14:04 GMT",
"from": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36268"
},
"title": "GCN CIRCULAR",
"number": "36268",
"subject": "IceCube Alert 240424.08: Global MASTER-Net observations report"
},
"message_text": "V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,\nG.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij\n(Lomonosov Moscow State University, SAI, Physics Department),\n\nR. Podesta, C.Lopez, F. Podesta, C.Francile\n(Observatorio Astronomico Felix Aguilar OAFA),\n\nR. Rebolo, M. Serra\n(The Instituto de Astrofisica de Canarias),\n\nD. Buckley\n(South African Astronomical Observatory),\n\nO.A. Gress, N.M. Budnev, O.Ershova\n(Irkutsk State University, API),\n\nL.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,\nA.R.Corella, L.H.Rodriguez\n(INAOE, Guillermo Haro Astrophysics Observatory),\n\nA. Tlatov, D. Dormidontov\n(Kislovodsk Solar Station of the Pulkovo Observatory),\n\nV. Yurkov, A. Gabovich\n(Blagoveschensk Educational State University)\n\nMASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the IceCube Alert 240424.08 (trigger No 50057906,21h 46m 07.20s , +03d 09m 43.2s, R=1.27) errorbox 24 sec after notice time and 62 sec after trigger time at 2024-04-24 01:50:28 UT, with upper limit up to 16.4 mag. The observations began at zenith distance = 71 deg. The sun altitude is -41.8 deg.\n\nThe galactic latitude b = -36 deg., longitude l = 60 deg.\n\n\nReal time updated cover map and OT discovered available here:\nhttps://master.sai.msu.ru/site/master2/observ.php?id$33992\n\nWe obtain a following upper limits.\n\nTmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment\n_________|_____________________|_____________________|____________________________________|_____|_______|_______|________\n\n 68 | 2024-04-24 01:50:28 | MASTER-SAAO | (21h 44m 16.95s , +02d 50m 02.1s) | C | 10 | 15.6 |\n 68 | 2024-04-24 01:50:28 | MASTER-SAAO | (21h 42m 29.64s , +03d 03m 19.8s) | C | 10 | 16.1 |\n 97 | 2024-04-24 01:50:58 | MASTER-SAAO | (21h 44m 16.99s , +02d 50m 02.0s) | C | 10 | 15.7 |\n 97 | 2024-04-24 01:50:58 | MASTER-SAAO | (21h 42m 29.67s , +03d 03m 19.2s) | C | 10 | 16.0 |\n 131 | 2024-04-24 01:51:27 | MASTER-SAAO | (21h 44m 17.02s , +02d 50m 02.2s) | C | 20 | 15.9 |\n 131 | 2024-04-24 01:51:27 | MASTER-SAAO | (21h 42m 29.67s , +03d 03m 19.2s) | C | 20 | 16.3 |\n 176 | 2024-04-24 01:52:07 | MASTER-SAAO | (21h 44m 17.05s , +02d 50m 02.2s) | C | 30 | 15.9 |\n 176 | 2024-04-24 01:52:07 | MASTER-SAAO | (21h 42m 29.69s , +03d 03m 19.0s) | C | 30 | 16.3 |\n 230 | 2024-04-24 01:52:56 | MASTER-SAAO | (21h 44m 17.08s , +02d 50m 02.0s) | C | 40 | 15.8 |\n 230 | 2024-04-24 01:52:56 | MASTER-SAAO | (21h 42m 29.69s , +03d 03m 18.5s) | C | 40 | 16.0 |\n 295 | 2024-04-24 01:53:55 | MASTER-SAAO | (21h 44m 17.11s , +02d 50m 01.9s) | C | 50 | 15.9 |\n 295 | 2024-04-24 01:53:55 | MASTER-SAAO | (21h 42m 29.68s , +03d 03m 18.3s) | C | 50 | 16.1 |\n 369 | 2024-04-24 01:55:05 | MASTER-SAAO | (21h 44m 17.12s , +02d 50m 01.6s) | C | 60 | 16.0 |\n 369 | 2024-04-24 01:55:05 | MASTER-SAAO | (21h 42m 29.65s , +03d 03m 17.9s) | C | 60 | 16.2 |\n 448 | 2024-04-24 01:56:24 | MASTER-SAAO | (21h 44m 17.11s , +02d 50m 01.4s) | C | 60 | 16.0 |\n 448 | 2024-04-24 01:56:24 | MASTER-SAAO | (21h 42m 29.58s , +03d 03m 17.5s) | C | 60 | 16.0 |\n 528 | 2024-04-24 01:57:44 | MASTER-SAAO | (21h 44m 17.11s , +02d 50m 01.4s) | C | 60 | 16.0 |\n 528 | 2024-04-24 01:57:44 | MASTER-SAAO | (21h 42m 29.53s , +03d 03m 17.3s) | C | 60 | 16.3 |\n 607 | 2024-04-24 01:59:03 | MASTER-SAAO | (21h 44m 17.09s , +02d 50m 01.1s) | C | 60 | 16.2 |\n 607 | 2024-04-24 01:59:03 | MASTER-SAAO | (21h 42m 29.48s , +03d 03m 17.0s) | C | 60 | 16.4 |\n 687 | 2024-04-24 02:00:22 | MASTER-SAAO | (21h 44m 17.07s , +02d 50m 00.7s) | C | 60 | 16.2 |\n 687 | 2024-04-24 02:00:22 | MASTER-SAAO | (21h 42m 29.44s , +03d 03m 16.7s) | C | 60 | 16.3 |\nFilter C is a clear (unfiltred) band.\n\n\nThe observation and reduction will continue.\nThe message may be cited.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36268.",
"published": "2024-04-24T02:14:18.730999Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T02:14:18.731024Z",
"modified": "2024-04-24T02:14:18.741264Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6897,
"topic": "gcn.circular",
"uuid": "c790b53f-d44c-4417-a352-5b5ac5bc98fc",
"title": "GRB 240421B: GRBAlpha detection",
"submitter": "Hop gcn.circular",
"authors": "Marianna DafÄÃková at Masaryk University <500025@mail.muni.cz>",
"data": {
"date": "24/04/24 03:33:17 GMT",
"from": "Marianna DafÄÃková at Masaryk University <500025@mail.muni.cz>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36269"
},
"title": "GCN CIRCULAR",
"number": "36269",
"subject": "GRB 240421B: GRBAlpha detection"
},
"message_text": "M. Dafcikova, J. Ripa, M. Kolar (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Duriskova, L. Szakszonova, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.\n\nThe long-duration GRB 240421B (Swift/BAT detection: GCN 36208; Fermi/GBM detection: GCN 36218; AstroSat detection: GCN 36223; Konus/Wind detection trigger at 2024-04-21 09:42:53.511 UT; INTEGRAL/SPI-ACS peak detection at 2024-04-21 ~09:42:54 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract).\n\nThe detection was confirmed at the peak time 2024-04-21 09:42:53.5 UTC. The T90 duration measured by GRBAlpha is 5.0 s and the overall significance during T90 reaches 11 sigma.\n\nThe light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB240421B_GCN.pdf\n\nAll GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/\nGRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. \n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36269.",
"published": "2024-04-24T03:33:34.448925Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T03:33:34.448938Z",
"modified": "2024-04-24T03:33:34.456722Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6898,
"topic": "gcn.circular",
"uuid": "006d8308-1a90-458b-b0d2-8e10d31357c6",
"title": "LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far",
"submitter": "Hop gcn.circular",
"authors": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
"data": {
"date": "24/04/24 03:44:51 GMT",
"from": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36270"
},
"title": "GCN CIRCULAR",
"number": "36270",
"subject": "LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far"
},
"message_text": "Y. L. Wang, W. J. Zhang, H. N. Yang, X. Pan, X. P. Xu, C. C. Jin, D. Y. Li, H. Sun, Y. Liu, Z. X. Ling, C. Zhang, W. Chen, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, J. J. Jin, T. Y. Lian, H. Y. Liu, M. J. Liu, Z. Z. Lv, X. Mao, H. W. Pan, W. X. Wang, S. X. Wen, Q. Y. Wu, Y. F. Xu, W. Yuan, M. Zhang, W. D. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Q. C. Shui (IHEP, CAS), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA), on behalf of the Einstein Probe team \n\nWe report on the X-ray upper limits from the ongoing observations of the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, for the three potential electromagnetic counterparts of the LIGO/Virgo/KAGRA candidate NSBH event S240422ed (The LIGO-Virgo-KAGRA Collaboration, GCN 36236), as reported in two previous GCN/LVC COUNTERPART NOTICEs (Swift-XRT #1, #2) and in GCN 36267 (Magellan #1).\n\nThrough our preliminary analysis of the WXT data, we found no significant X-ray counterpart at the position of these sources. The upper limits in 0.5-4 keV at the 90% confidence level are derived from the accumulated exposure from 2024-04-23 00:37:26 (UTC) to 2024-04-23 23:48:09 (UTC). \n\nThe flux upper limits at the 90% confidence level are detailed as follows. \nSource | R.A. (J2000) | Dec. (J2000) | Exposure (s) | Upper limit (erg/s/cm2) \n--------------------------------------------------------------------------------------\nSwift-XRT #1 | 120.3245 | -28.1765 | 43000 | 4.4 x 10^-12\nSwift-XRT #2 | 126.2283 | -23.1542 | 27000 | 5.6 x 10^-12\nMagellan #1 | 119.0233 | -22.8983 | 37000 | 4.7 x 10^-12\n\nFor the potential optical counterpart found by Magellan (GCN 36267), we have triggered a quick follow-up observation with the Follow-up X-ray Telescope (FXT) of EP. Further results will be reported after the observation is completed.\n\nThe above observations were made with the WXT instrument during the commissioning phase of EP. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36270.",
"published": "2024-04-24T03:45:07.868153Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T03:45:07.868174Z",
"modified": "2024-04-24T03:45:07.876114Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6899,
"topic": "gcn.circular",
"uuid": "698507a3-dc18-44de-a493-57d1cd9e222e",
"title": "LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61",
"submitter": "Hop gcn.circular",
"authors": "Dong Xu at NAOC/CAS <dxu@nao.cas.cn>",
"data": {
"date": "24/04/24 03:54:34 GMT",
"from": "Dong Xu at NAOC/CAS <dxu@nao.cas.cn>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36271"
},
"title": "GCN CIRCULAR",
"number": "36271",
"subject": "LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61"
},
"message_text": "X. Liu, Z.P. Zhu, S.Q. Jiang, J. An, S.Y. Fu, D. Xu (NAOC), J.P.U. Fynbo (DAWN/NBI), N. Koivisto, A. A. Djupvik (NOT) report:\n\nWe observed the location of the Swift/XRT source 61 (labelled S240422ed_X61) at coordinates RA, Dec = 120.3245d, -28.1765d (J2000; https://gcn.gsfc.nasa.gov/other/S240422ed.counterpart) which is within the error region of the LIGO/Virgo/KAGRA event S240422ed (GCN 36236, GCN 36240). Observations started at 20:41:38.400 UT on 2024-04-23, i.e., ~ 23.11 hr after the LVK trigger time, and a series of frames were obtained in J-/H-/K- bands.\n\nPreliminary data analysis shows that there is no credible source detected at the XRT position in the stacked J-band image, down to a limiting magnitude of J ~ 18 mag, calibrated with the 2MASS field.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36271.",
"published": "2024-04-24T03:54:53.184560Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T03:54:53.184577Z",
"modified": "2024-04-24T03:54:53.192583Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6900,
"topic": "gcn.circular",
"uuid": "78c99590-d96c-4f86-ae0d-1bc4fdfb8384",
"title": "LIGO/Virgo/KAGRA S240422ed: Potential Magellan candidates from GCN 36263 are unrelated.",
"submitter": "Hop gcn.circular",
"authors": "Harsh Kumar at Center for Astrophysics | Harvard & Smithsonian <harshkosli13@gmail.com>",
"data": {
"date": "24/04/24 04:38:42 GMT",
"from": "Harsh Kumar at Center for Astrophysics | Harvard & Smithsonian <harshkosli13@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36272"
},
"title": "GCN CIRCULAR",
"number": "36272",
"subject": "LIGO/Virgo/KAGRA S240422ed: Potential Magellan candidates from GCN 36263 are unrelated."
},
"message_text": "H. Kumar, D. Hiramatsu, E. Berger, A. Villar, K. D. Soto, S. K. Yadavalli, M. Hussaini, A. Gagliano, C. Ransome (Harvard) report:\n\nWe used the LDSS-3 imager on the 6.5m Magellan Clay telescope to follow-up on our two potential candidates, see H. Kumar et al. (GCN #36263). We obtained 150-second r-, i-band images and compared them to those obtained in the previous night. We did not find any source at the location of these candidates after image subtraction performed between two epoch images, indicating the non-transient nature of the sources. Therefore, we conclude that both the sources are unrelated to the S240422ed and thus, can be ruled out.\n\nWe thank Marcelo Mora, Povilas Palunas, and the LCO staff for rapid execution of these observations.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36272.",
"published": "2024-04-24T04:38:58.314162Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T04:38:58.314183Z",
"modified": "2024-04-24T04:38:58.322733Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6901,
"topic": "gcn.circular",
"uuid": "f9118001-0445-45f3-8c1d-6e0d3da45d3c",
"title": "LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates",
"submitter": "Hop gcn.circular",
"authors": "Antonella Palmese at Carnegie Mellon University <apalmese@andrew.cmu.edu>",
"data": {
"date": "24/04/24 04:58:04 GMT",
"from": "Antonella Palmese at Carnegie Mellon University <apalmese@andrew.cmu.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36273"
},
"title": "GCN CIRCULAR",
"number": "36273",
"subject": "LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates"
},
"message_text": "Lei Hu (CMU), Tomás Cabrera (CMU), Brendan O'Connor (CMU), Igor Andreoni (UMD), Antonella Palmese (CMU), Keerthi Kunnumkai (CMU) report on behalf of the GW-MMADS team:\n\n\nWe continued the follow-up of the LIGO/Virgo/KAGRA event S240422ed (GCN 36236, GCN 36240) with DECam as part of the GW-MMADS survey program (Palmese et al., GCN 36245). New pointings taken between 2024-04-23 23:15 and 2024-04-24 03:46 UTC have been reported to the TreasureMap (Wyatt et al., 2020): https://treasuremap.space/alerts?graceids=S240422ed\n\nWe ran the SFFT difference imaging (Hu et al. 2022) on the available images from the first night of observations (between 2023-04-22 23:37 and 2024-04-23 03:40 UTC; GCN 36245), filtered out likely stars and moving objects, and visually inspected the remaining transients. \n\nWe reported on TNS new transients within the LVK 95% CI area, and report here the candidate counterparts with at least two detections and possibly associated with a low-redshift galaxy from the NED LVS catalog (Cook et al. 2023):\n\n+-------------------------+------------+------------+-----------+-----------+\n| id | tns | ra | dec | comment |\n|-------------------------+------------+------------+-----------+-----------|\n| T202404230842302m153558 | AT 2024hdk | 130.625724 | -15.59953 | |\n| T202404230829126m213023 | AT 2024hdn | 127.302473 | -21.50639 | |\n| T202404230826379m205002 | AT 2024hdm | 126.65801 | -20.83375 | |\n| T202404230821534m300608 | AT 2024hdl | 125.472700 | -30.10220 | * |\n| T202404220803280m260044 | AT 2024hdo | 120.866797 | -26.01212 | |\n| T202404220803131m241958 | AT 2024hdr | 120.804560 | -24.33268 | nuclear |\n| T202404220802104m271528 | AT 2024hdp | 120.543455 | -27.25787 | |\n| T202404220743147m254551 | AT 2024hdq | 115.811388 | -25.76403 | nuclear |\n+-------------------------+------------+------------+-----------+-----------+\n\n* This object was detected in 2 observations separated by <15 min and cannot be excluded as a moving object.\n\nFurther data reduction is underway.\n\nWe thank the CTIO and NOIRLab staff for supporting these observations and the data calibrations.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36273.",
"published": "2024-04-24T04:58:18.445216Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T04:58:18.445229Z",
"modified": "2024-04-24T04:58:18.454754Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6902,
"topic": "gcn.circular",
"uuid": "b09ff989-6ed4-4b4b-a15c-b60d5d33d1e3",
"title": "LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a",
"submitter": "Hop gcn.circular",
"authors": "Janet Chen at National Central University <janetstars@gmail.com>",
"data": {
"date": "24/04/24 06:00:35 GMT",
"from": "Janet Chen at National Central University <janetstars@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36274"
},
"title": "GCN CIRCULAR",
"number": "36274",
"subject": "LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a"
},
"message_text": "Steve Schulze (CIERA, Northwestern) and Nial R. Tanvir (University of Leicester) report on behalf of the ENGRAVE GW collaboration:\n\nWe detect an object at the position of Mag24a (Piro et al., GCN 36267) in archival stacked r- and z-band images of the Dark Energy Camera Plane Survey 2 (DECaPS2; Saydjari et al. 2022).\n\nhttps://www.legacysurvey.org/viewer?ra\u00119.0234&dec=-22.8979&layerÞcaps2&zoom\u0016&sources-dr7&sources-dr8&sources-dr9&sources-dr9n&sources-dr9s&sources-dr10&sources-dr10-south\n\nThe diffuse emission of the galaxy at RA, Decl. (J2000) = 7:56:05.744, -22:54:03.51 hinders accurate photometry. We measure r = 22.64 +- 0.08 and z = 21.79 +- 0.08 (not corrected for MW extinction) using a circular aperture with a diameter of 1.1 arcsec and stars from PanSTARRS.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36274.",
"published": "2024-04-24T06:00:52.300833Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T06:00:52.300848Z",
"modified": "2024-04-24T06:00:52.310461Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6903,
"topic": "gcn.circular",
"uuid": "34afac59-6933-4920-8546-06fc8e787a7c",
"title": "LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a",
"submitter": "Hop gcn.circular",
"authors": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"data": {
"date": "24/04/24 06:59:39 GMT",
"from": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36275"
},
"title": "GCN CIRCULAR",
"number": "36275",
"subject": "LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a"
},
"message_text": "A. L. Piro, J. D. Simon (Carnegie), A. Polin (Carnegie/Purdue), D. A. Coulter (STScI), M. R. Drout (Toronto), R. J. Foley, and C. Rojas-Bravo (UC Santa Cruz)\n\nreport on behalf of the Carnegie Gravitational wave ElectroMagnetic follow-up (CGEM) and the One-Meter Two-Hemisphere (1M2H) collaborations:\n\nWe have continued to image Mag24a (GCN 36267), the potential optical counterpart to the candidate gravitational wave event S240422ed (GCN 36236) that was found with a galaxy-targeted search using Teglon [1] with the LDSS-3 imager on the 6.5m Magellan Clay telescope (GCN 36244). The times of the images on 20240424 UT, filters observed, and length of exposures are as follows.\n\nUT Start Filter Exposure time (sec)\n02:00:46 r 300\n02:06:40 g 300\n02:18:01 r 300\n02:24:24 z 120\n02:26:57 z 120\n02:36:55 i 300\n02:42:28 i 300\n\nWe detect Mag24a in the i and z band images. We update the magnitude measurement from GCN 36267 to i = 22.2 mag and measure z = 22.3 mag from the newly acquired images, resulting in a Milky Way reddening corrected color of i-z = -0.29 mag.\n\nAs pointed out by Schulze & Tanvir (GCN 36274), a source is detected at this position in the DECaPS survey, with AB magnitudes of r#.2, i\".5, and z\".0. Given the similarity of these measurements to our detections, we conclude that Mag24a is likely not a transient.\n\nWe thank Marcelo Mora, Povilas Palunas, and the rest of the LCO staff for making these observations possible.\n\n[1] Coulter, D. A. (2021), https://zenodo.org/records/5683508\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36275.",
"published": "2024-04-24T06:59:54.701381Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T06:59:54.701396Z",
"modified": "2024-04-24T06:59:54.709511Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6904,
"topic": "gcn.circular",
"uuid": "48ccb860-cbe2-4e31-a17b-3688e137a4e8",
"title": "LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a",
"submitter": "Hop gcn.circular",
"authors": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"data": {
"date": "24/04/24 07:19:16 GMT",
"from": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36276"
},
"title": "GCN CIRCULAR",
"number": "36276",
"subject": "LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a"
},
"message_text": "Viraj Karambelkar (Caltech), Sam Rose (Caltech), on behalf of a larger\ncollaboration.\n\nWe imaged the source Mag24a (GCN 36267, 36274, 36275), reported as a\ncandidate optical counterpart to the LVK gravitational wave event S240422ed\n(GCN 36236) with the Wide-Field Infrared Camera (WIRC) on the 200-inch Hale\nTelescope at Palomar Observatory on UTC 2024-04-24T04:24:14.\n\nWe do not detect any source at the location of Mag24a, to a depth of J 21.2 mag (AB).\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36276.",
"published": "2024-04-24T07:19:37.845043Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T07:19:37.845055Z",
"modified": "2024-04-24T07:19:37.854073Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6905,
"topic": "gcn.circular",
"uuid": "59859af5-07a9-44e4-9766-74b15b4992a4",
"title": "LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region",
"submitter": "Hop gcn.circular",
"authors": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
"data": {
"date": "24/04/24 08:17:05 GMT",
"from": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36277"
},
"title": "GCN CIRCULAR",
"number": "36277",
"subject": "LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region"
},
"message_text": "W. J. Zhang, Y. L. Wang, H. N. Yang, X. Pan, X. P. Xu, C. C. Jin, D. Y. Li, H. Sun, Y. Liu, Z. X. Ling, C. Zhang, W. Chen, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, J. J. Jin, T. Y. Lian, H. Y. Liu, M. J. Liu, Z. Z. Lv, X. Mao, H. W. Pan, W. X. Wang, S. X. Wen, Q. Y. Wu, Y. F. Xu, W. Yuan, M. Zhang, W. D. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Q. C. Shui (IHEP, CAS), B. Zhang (UNLV), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA), on behalf of the Einstein Probe team \n\nWe report on the X-ray upper limits derived from early observations with the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission for the sky region of the LIGO/Virgo/KAGRA candidate NSBH event S240422ed (The LIGO-Virgo-KAGRA Collaboration, GCN 36236). \n\nA real-time EP-WXT observation serendipitously covered ~90 square degrees in the 90% credible region of the updated LVK sky localization (The LIGO-Virgo-KAGRA Collaboration, GCN 36240) from 2024-04-22 21:21:23 UTC with an exposure time of 5900 seconds, 830 s before the trigger time of the gravitational wave (GW) event (T0). However, this observation was interrupted by the SAA passage from 2024-04-22 21:31:23 UTC to 2024-04-22 22:00:00 UTC, so only the data within [T0-830 s, T0-230 s] (Obs-1a) and [T0+1487 s, T0+36202 s] (Obs-1b) are useful. No significant X-ray counterpart was detected in these good time intervals. Flux upper limits in 0.5-4 keV at the 90% confidence level are derived from good exposure time before and after the interruption of the observation.\n\nDuring the above observation, an EP Target-of-Opportunity observation (Obs-2) was triggered on the LVK sky localization region, with the WXT field-of-view covered almost all of the 90% credible region of GW localization. Through our sebsequent analysis of the WXT data, no significant X-ray counterparts were found. A flux upper limit in 0.5-4 keV at the 90% confidence level is derived from this observation.\n\nThe flux upper limits at the 90% confidence level are detailed as follows. \nNo. | Start time (UTC) | End time (UTC) | Effective Exposure (s) | Upper limit (erg/s/cm2) \n--------------------------------------------------------------------------------------------------------------------\nObs-1a | 2024-04-22 21:21:23 | 2024-04-22 21:31:23 | 600 | 4.1 x 10^-11\nObs-1b | 2024-04-22 22:00:00 | 2024-04-23 07:38:35 | 5300 | 1.3 x 10^-11\nObs-2 | 2024-04-23 00:37:26 | 2024-04-23 05:24:11 | 5100 | 1.3 x 10^-11\n\nEP is currently observing a list of galaxies within the 90% GW region with its Follow-up X-ray Telescope (FXT). The WXT field-of-view is covering a large fraction of this GW region simultaneously. The monitoring campaign and subsequent data analysis are ongoing. Further results will be reported later.\n\nThe above observations were made with the WXT instrument during the commissioning phase of EP. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36277.",
"published": "2024-04-24T08:17:20.703482Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T08:17:20.703494Z",
"modified": "2024-04-24T08:17:20.712813Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6906,
"topic": "gcn.circular",
"uuid": "12f0dcfe-f13e-43c1-bebc-8690dd073409",
"title": "LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts",
"submitter": "Hop gcn.circular",
"authors": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"data": {
"date": "24/04/24 08:42:33 GMT",
"from": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36278"
},
"title": "GCN CIRCULAR",
"number": "36278",
"subject": "LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts"
},
"message_text": "P.A. Evans (U. Leicester), K.L. Page (U. Leicester), J.A. Kennea (PSU),\nA. Tohuvavohu (U. Toronto), S.B. Cenko (NASA/GSFC), R.A.J. Eyles-Ferris\n(U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini\n(INAF-OAB), A.A. Breeveld (UCL-MSSL), S. Campana (INAF-OAB), M. De\nPasquale (University of Messina), S. Dichiara (PSU), P. DâAvanzo\n(INAF-OAB), A. DâAì (INAF-IASFPA) , V. DâElia (ASI-SSDC &\nINAF-OAR), C. Gronwall (PSU), D. Hartmann (Clemson University), N.\nKlingler (NASA-GSFC / UMBC / CRESST II), N.P.M. Kuin (UCL-MSSL), S.\nLaha (NASA/GSFC), S.R. Oates (U. Birmingham), J.P. Osborne (U.\nLeicester), P. OâBrien (U. Leicester), M.J. Page (UCL-MSSL), G. Raman\n(PSU) S. Ronchini (PSU), T. Sbarrato (INAF-OAB), B. Sbarufatti\n(INAF-OAB), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (U\nTor Vergata, INAF) report on behalf of the Swift team:\n\nSwift has carried out 92 observations of the LVC error region for the\nGW trigger S240422ed convolved with the 2MPZ catalogue (Bilicki et al.\n2014, ApJS, 210, 9), using 76 fields from the 'BAYESTAR' GW\nlocalisation map and 16 fields from the 'ligo-skymap-from-samples' GW\nlocalisation map. As these are 3D skymaps, galaxy distances were taken\ninto account in selecting which ones to observe. The observations\ncurrently span from 10 ks to 90 ks after the LVC trigger, and the XRT\nhas covered 10.1 deg^2 on the sky (corrected for overlaps). This covers\n4.5% of the probability in the 'ligo-skymap-from-samples' (version\nligo-skymap-from-samples.fits.gz) skymap, and 19% after convolving with\nthe 2MPZ galaxy catalogue, as described by Evans et al. (2016, MNRAS, \n462, 1591). Using the earlier 'BAYESTAR' (version BAYESTAR.fits.gz)\nskymap our observations cover 5.3% of the probability (19% when\nconvolved). These pointings and associated metadata have been reported\nto the Treasure Map (Wyatt et al., 2020, ApJ, 894, 127;\nhttp://treasuremap.space/alerts?graceids=S240422ed).\n\n3 rank 2 sources have been found. These are candidates to be the\ncounterpart to the GW trigger. Details of these sources are:\n \n Source S240422ed_X61:\n =====================\n RA: \t 120.3245 ( = 08h 01m 17.88s) J2000\n Dec:\t -28.1765 ( = -28d 10' 35.4\") J2000\n Error:\t 5.1 (arcsec, radius, 90% confidence).\n Peak Rate:\t 8.3e-02 +/- 3.0e-02 ct s^-1 (0.3-10 keV)\n Peak Flux:\t 3.5e-12 +/- 1.3e-12 erg cm^-2 s^-1 (0.3-10 keV)\n Catalogued: No\n RASS UL:\t 3.3e-02 ct s^-1 (converted to XRT; 0.3-10 keV)\n\t\t so the source is not above the RASS 3-sigma\n\t\t upper limit.\n\n The source IS FADING at the 3.0-sigma level.\n\n NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy\n which is consistent (within 3-sigma) with the distance to the GW\n object.\n \n Source S240422ed_X101:\n ======================\n RA: \t 122.3954 ( = 08h 09m 34.90s) J2000\n Dec:\t -24.3272 ( = -24d 19' 37.9\") J2000\n Error:\t 6.6 (arcsec, radius, 90% confidence).\n Peak Rate:\t 1.0e-01 +/- 3.1e-02 ct s^-1 (0.3-10 keV)\n Peak Flux:\t 4.4e-12 +/- 1.3e-12 erg cm^-2 s^-1 (0.3-10 keV)\n Catalogued: No\n RASS UL:\t 2.6e-02 ct s^-1 (converted to XRT; 0.3-10 keV)\n\t\t so the source is not above the RASS 3-sigma\n\t\t upper limit.\n\n The source IS FADING at the 3.5-sigma level.\n\n NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy\n which is consistent (within 3-sigma) with the distance to the GW\n object.\n \n Source S240422ed_X190:\n ======================\n RA: \t 121.2770 ( = 08h 05m 06.48s) J2000\n Dec:\t -26.1203 ( = -26d 07' 13.1\") J2000\n Error:\t 5.3 (arcsec, radius, 90% confidence).\n Peak Rate:\t 2.0e+00 +/- 5.2e-01 ct s^-1 (0.3-10 keV)\n Peak Flux:\t 8.4e-11 +/- 2.2e-11 erg cm^-2 s^-1 (0.3-10 keV)\n Catalogued: No\n RASS UL:\t 2.2e-02 ct s^-1 (converted to XRT; 0.3-10 keV)\n\t\t so the source is not above the RASS 3-sigma\n\t\t upper limit.\n\n There is no evidence for fading.\n\n NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy\n which is consistent (within 3-sigma) with the distance to the GW\n object.\n\n NOTE: This source is in a very noisy XRT field and it may not\n be real: we will request a follow-up observation.\n\n\nIn total, we have detected 232 X-ray sources. Each source is assigned a\nrank of 1-4 which describes how likely it is to be related to the GW\ntrigger, with 1 being the most likely and 4 being the least likely. The\nranks are described at https://www.swift.ac.uk/ranks.php.\n\nWe have found:\n\n * 0 sources of rank 1\n * 3 sources of rank 2\n * 221 sources of rank 3\n * 8 sources of rank 4\n\n\nRANK 3 sources\n==============\n\nThese are uncatalogued X-ray sources, however they are not brighter\nthan previous upper limits, so do not stand out as likely counterparts\nto the GW trigger.\n\n| Source ID\t | RA\t\t | Dec \t | Err90 |\n| S240422ed_X2 | 08h 04m 43.19s | -23d 37' 24.0\" |\t6.7\" |\n| S240422ed_X4 | 08h 08m 39.34s | -18d 23' 50.4\" |\t6.4\" |\n| S240422ed_X5 | 07h 58m 51.02s | -22d 17' 16.6\" |\t8.4\" |\n| S240422ed_X6 | 07h 58m 47.06s | -22d 19' 26.6\" |\t7.5\" |\n| S240422ed_X7 | 07h 58m 41.54s | -22d 13' 08.6\" |\t8.7\" |\n| S240422ed_X8 | 07h 58m 19.82s | -22d 24' 05.6\" |\t9.0\" |\n| S240422ed_X9 | 07h 58m 00.71s | -22d 21' 34.1\" |\t6.7\" |\n| S240422ed_X10 | 08h 00m 49.40s | -22d 20' 59.6\" |\t6.1\" |\n| S240422ed_X11 | 08h 00m 22.80s | -22d 33' 38.2\" |\t7.5\" |\n| S240422ed_X12 | 08h 07m 15.82s | -15d 17' 34.9\" |\t6.6\" |\n| S240422ed_X14 | 07h 58m 02.82s | -21d 57' 15.2\" |\t7.2\" |\n| S240422ed_X16 | 07h 57m 56.03s | -22d 03' 12.6\" |\t6.2\" |\n| S240422ed_X17 | 07h 58m 19.62s | -22d 11' 25.7\" |\t6.0\" |\n| S240422ed_X18 | 07h 57m 56.36s | -22d 04' 01.4\" |\t8.0\" |\n| S240422ed_X21 | 07h 57m 54.83s | -22d 10' 00.4\" |\t8.5\" |\n| S240422ed_X22 | 08h 15m 58.64s | -17d 22' 35.3\" |\t5.9\" |\n| S240422ed_X23 | 08h 09m 56.11s | -21d 32' 55.6\" |\t8.8\" |\n| S240422ed_X24 | 08h 10m 23.64s | -18d 19' 04.7\" |\t7.6\" |\n| S240422ed_X25 | 08h 10m 14.18s | -18d 21' 09.1\" | 10.6\" |\n| S240422ed_X26 | 08h 09m 51.65s | -18d 11' 17.5\" |\t9.1\" |\n| S240422ed_X27 | 08h 09m 39.34s | -18d 17' 48.1\" |\t8.2\" |\n| S240422ed_X28 | 08h 09m 41.22s | -18d 25' 48.1\" |\t7.0\" |\n| S240422ed_X29 | 08h 09m 12.43s | -18d 23' 13.5\" |\t8.8\" |\n| S240422ed_X30 | 08h 09m 47.31s | -18d 26' 04.3\" |\t6.9\" |\n| S240422ed_X31 | 08h 09m 33.65s | -18d 24' 32.0\" |\t6.1\" |\n| S240422ed_X32 | 07h 58m 47.43s | -22d 08' 43.6\" | 15.9\" |\n| S240422ed_X33 | 08h 05m 01.75s | -28d 25' 44.4\" |\t6.8\" |\n| S240422ed_X34 | 08h 04m 34.26s | -28d 12' 37.1\" |\t9.2\" |\n| S240422ed_X35 | 08h 05m 33.59s | -28d 13' 27.9\" |\t7.3\" |\n| S240422ed_X36 | 08h 05m 42.68s | -28d 19' 58.0\" |\t7.6\" |\n| S240422ed_X37 | 08h 05m 09.97s | -28d 16' 48.6\" |\t5.7\" |\n| S240422ed_X38 | 08h 05m 45.16s | -28d 21' 01.4\" |\t6.6\" |\n| S240422ed_X39 | 08h 05m 52.57s | -28d 18' 46.9\" |\t6.0\" |\n| S240422ed_X40 | 08h 04m 41.41s | -28d 11' 57.8\" |\t5.5\" |\n| S240422ed_X41 | 08h 05m 42.43s | -28d 24' 19.3\" |\t6.5\" |\n| S240422ed_X42 | 08h 04m 52.35s | -28d 28' 09.7\" |\t5.7\" |\n| S240422ed_X43 | 08h 04m 53.26s | -28d 10' 57.2\" |\t5.6\" |\n| S240422ed_X44 | 08h 09m 09.81s | -18d 14' 19.8\" |\t7.3\" |\n| S240422ed_X45 | 08h 09m 23.24s | -18d 20' 00.8\" |\t6.1\" |\n| S240422ed_X46 | 07h 57m 28.64s | -22d 12' 32.3\" |\t6.0\" |\n| S240422ed_X47 | 07h 58m 40.23s | -22d 22' 38.5\" | 13.7\" |\n| S240422ed_X48 | 07h 59m 34.40s | -22d 17' 46.2\" | 11.7\" |\n| S240422ed_X49 | 07h 58m 24.50s | -22d 23' 26.8\" |\t6.8\" |\n| S240422ed_X50 | 08h 00m 13.07s | -22d 32' 47.5\" |\t6.5\" |\n| S240422ed_X51 | 08h 05m 21.65s | -23d 53' 32.3\" | 17.6\" |\n| S240422ed_X52 | 08h 04m 21.05s | -27d 51' 35.2\" |\t7.2\" |\n| S240422ed_X53 | 08h 03m 36.15s | -27d 42' 01.7\" |\t6.4\" |\n| S240422ed_X54 | 08h 03m 47.04s | -27d 55' 19.2\" |\t9.0\" |\n| S240422ed_X55 | 08h 02m 01.17s | -28d 22' 57.3\" |\t5.1\" |\n| S240422ed_X56 | 08h 05m 41.74s | -28d 14' 26.6\" |\t6.3\" |\n| S240422ed_X57 | 08h 01m 49.87s | -29d 25' 59.9\" | 18.1\" |\n| S240422ed_X58 | 08h 02m 57.63s | -29d 26' 03.6\" |\t8.8\" |\n| S240422ed_X59 | 08h 01m 50.05s | -28d 18' 01.6\" |\t5.9\" |\n| S240422ed_X60 | 08h 02m 04.53s | -29d 20' 01.5\" |\t8.0\" |\n| S240422ed_X62 | 08h 01m 53.82s | -28d 22' 53.5\" |\t5.9\" |\n| S240422ed_X63 | 08h 00m 50.67s | -30d 30' 24.5\" |\t7.6\" |\n| S240422ed_X64 | 08h 05m 05.17s | -28d 28' 42.9\" |\t5.7\" |\n| S240422ed_X65 | 08h 01m 23.18s | -28d 27' 21.4\" | 13.0\" |\n| S240422ed_X66 | 08h 02m 40.39s | -22d 35' 42.0\" |\t5.8\" |\n| S240422ed_X67 | 08h 02m 29.38s | -25d 57' 49.1\" | 10.4\" |\n| S240422ed_X68 | 08h 08m 43.37s | -23d 37' 34.1\" |\t5.5\" |\n| S240422ed_X69 | 08h 07m 30.28s | -23d 34' 03.4\" |\t6.6\" |\n| S240422ed_X70 | 08h 07m 46.09s | -23d 33' 27.0\" | 21.2\" |\n| S240422ed_X71 | 08h 03m 12.73s | -27d 44' 20.2\" |\t5.6\" |\n| S240422ed_X72 | 08h 03m 50.59s | -27d 40' 12.6\" |\t6.0\" |\n| S240422ed_X73 | 08h 04m 15.34s | -27d 48' 20.9\" |\t6.5\" |\n| S240422ed_X74 | 08h 03m 42.64s | -27d 47' 17.4\" |\t9.3\" |\n| S240422ed_X75 | 08h 03m 39.57s | -27d 40' 24.7\" |\t5.5\" |\n| S240422ed_X76 | 08h 03m 09.92s | -27d 51' 26.5\" |\t5.8\" |\n| S240422ed_X78 | 08h 03m 44.46s | -27d 38' 25.0\" |\t6.0\" |\n| S240422ed_X79 | 08h 04m 19.22s | -27d 45' 54.7\" | 14.0\" |\n| S240422ed_X81 | 08h 03m 55.28s | -27d 39' 33.2\" |\t5.5\" |\n| S240422ed_X83 | 08h 03m 22.60s | -27d 40' 46.2\" |\t5.1\" |\n| S240422ed_X84 | 08h 04m 20.06s | -25d 14' 47.2\" |\t6.6\" |\n| S240422ed_X85 | 08h 04m 09.38s | -25d 09' 29.1\" |\t6.0\" |\n| S240422ed_X86 | 08h 05m 05.57s | -25d 13' 20.9\" |\t6.2\" |\n| S240422ed_X87 | 08h 05m 07.42s | -25d 10' 46.8\" |\t6.2\" |\n| S240422ed_X88 | 08h 04m 49.42s | -25d 20' 49.6\" |\t5.6\" |\n| S240422ed_X89 | 08h 06m 24.02s | -25d 57' 50.6\" |\t5.9\" |\n| S240422ed_X90 | 08h 05m 30.96s | -25d 52' 08.9\" |\t6.9\" |\n| S240422ed_X91 | 08h 05m 53.97s | -26d 07' 17.3\" |\t5.4\" |\n| S240422ed_X92 | 08h 06m 26.93s | -26d 02' 22.8\" |\t6.6\" |\n| S240422ed_X93 | 08h 05m 50.43s | -25d 50' 09.4\" |\t6.5\" |\n| S240422ed_X94 | 08h 05m 17.51s | -26d 01' 16.5\" |\t5.6\" |\n| S240422ed_X95 | 08h 05m 17.32s | -25d 57' 33.6\" |\t7.9\" |\n| S240422ed_X96 | 08h 05m 46.88s | -25d 50' 22.5\" |\t7.9\" |\n| S240422ed_X97 | 08h 05m 44.78s | -25d 49' 06.8\" |\t7.4\" |\n| S240422ed_X98 | 08h 06m 22.66s | -26d 00' 00.5\" |\t9.0\" |\n| S240422ed_X99 | 08h 06m 29.45s | -26d 00' 10.6\" |\t8.8\" |\n| S240422ed_X100 | 08h 05m 02.54s | -25d 56' 13.9\" |\t 8.1\" |\n| S240422ed_X103 | 08h 02m 37.62s | -26d 04' 28.5\" |\t 7.8\" |\n| S240422ed_X104 | 08h 02m 52.95s | -25d 52' 07.3\" |\t 5.9\" |\n| S240422ed_X105 | 08h 07m 25.94s | -23d 38' 14.9\" |\t 9.5\" |\n| S240422ed_X106 | 08h 08m 06.73s | -23d 27' 56.3\" |\t 6.7\" |\n| S240422ed_X107 | 08h 05m 17.75s | -25d 56' 42.1\" |\t 5.7\" |\n| S240422ed_X113 | 08h 25m 27.91s | -20d 20' 51.8\" |\t 5.4\" |\n| S240422ed_X114 | 08h 24m 06.00s | -20d 17' 30.8\" |\t 6.1\" |\n| S240422ed_X115 | 08h 17m 16.80s | -18d 34' 49.1\" |\t 6.5\" |\n| S240422ed_X116 | 08h 16m 57.94s | -18d 36' 35.4\" |\t 6.1\" |\n| S240422ed_X117 | 08h 10m 17.16s | -18d 08' 25.3\" |\t 6.5\" |\n| S240422ed_X119 | 08h 11m 02.83s | -18d 06' 30.8\" |\t 6.4\" |\n| S240422ed_X120 | 08h 10m 40.03s | -17d 57' 24.6\" |\t 7.9\" |\n| S240422ed_X121 | 08h 10m 18.17s | -18d 16' 06.4\" |\t 6.7\" |\n| S240422ed_X122 | 08h 10m 03.03s | -18d 11' 37.4\" |\t15.7\" |\n| S240422ed_X123 | 08h 10m 16.23s | -18d 19' 39.6\" |\t 6.8\" |\n| S240422ed_X124 | 08h 10m 24.70s | -18d 16' 17.7\" |\t 6.1\" |\n| S240422ed_X125 | 08h 11m 35.67s | -17d 56' 05.8\" |\t 5.8\" |\n| S240422ed_X126 | 08h 10m 38.19s | -18d 22' 21.0\" |\t 5.8\" |\n| S240422ed_X127 | 08h 09m 55.62s | -18d 18' 02.4\" |\t 9.0\" |\n| S240422ed_X128 | 08h 11m 19.81s | -18d 00' 36.6\" |\t 6.0\" |\n| S240422ed_X129 | 08h 09m 56.24s | -18d 15' 51.5\" |\t 8.6\" |\n| S240422ed_X130 | 08h 10m 14.29s | -18d 15' 08.6\" |\t 7.2\" |\n| S240422ed_X131 | 08h 10m 05.28s | -18d 16' 22.0\" |\t 6.6\" |\n| S240422ed_X132 | 08h 10m 54.98s | -17d 46' 59.2\" |\t 6.0\" |\n| S240422ed_X133 | 08h 10m 55.47s | -17d 55' 36.3\" |\t 5.3\" |\n| S240422ed_X134 | 08h 09m 48.80s | -18d 09' 58.4\" |\t 6.8\" |\n| S240422ed_X135 | 08h 10m 02.96s | -18d 16' 16.8\" |\t 6.5\" |\n| S240422ed_X136 | 08h 11m 40.95s | -18d 00' 38.9\" |\t 5.0\" |\n| S240422ed_X137 | 08h 10m 59.88s | -17d 47' 27.4\" |\t 6.2\" |\n| S240422ed_X138 | 08h 10m 21.49s | -18d 20' 23.1\" |\t 5.7\" |\n| S240422ed_X140 | 08h 10m 28.48s | -18d 01' 55.9\" |\t 5.7\" |\n| S240422ed_X141 | 08h 11m 20.29s | -18d 03' 59.4\" |\t 5.7\" |\n| S240422ed_X142 | 08h 10m 13.99s | -18d 09' 21.1\" |\t 6.3\" |\n| S240422ed_X143 | 08h 09m 55.96s | -18d 12' 27.7\" |\t 6.3\" |\n| S240422ed_X144 | 08h 10m 04.29s | -18d 18' 33.4\" |\t 7.1\" |\n| S240422ed_X145 | 08h 10m 12.97s | -18d 16' 47.6\" |\t 6.7\" |\n| S240422ed_X146 | 08h 10m 54.91s | -18d 22' 38.5\" |\t 6.0\" |\n| S240422ed_X147 | 08h 10m 04.19s | -18d 07' 18.2\" |\t11.3\" |\n| S240422ed_X148 | 08h 10m 08.39s | -18d 18' 15.0\" |\t 6.3\" |\n| S240422ed_X149 | 08h 11m 20.72s | -18d 17' 09.0\" |\t 9.5\" |\n| S240422ed_X150 | 08h 09m 50.26s | -18d 15' 21.7\" |\t 8.8\" |\n| S240422ed_X151 | 08h 10m 01.15s | -18d 19' 55.1\" |\t 6.6\" |\n| S240422ed_X152 | 08h 11m 24.09s | -17d 49' 54.0\" |\t 6.7\" |\n| S240422ed_X153 | 08h 10m 09.02s | -18d 21' 06.4\" |\t 6.1\" |\n| S240422ed_X154 | 08h 12m 14.52s | -18d 48' 29.7\" |\t 8.7\" |\n| S240422ed_X155 | 08h 12m 40.59s | -18d 38' 36.0\" |\t12.8\" |\n| S240422ed_X156 | 08h 13m 21.01s | -18d 56' 52.6\" |\t 8.6\" |\n| S240422ed_X157 | 08h 12m 48.62s | -18d 59' 37.5\" |\t 7.3\" |\n| S240422ed_X158 | 08h 12m 28.74s | -18d 48' 37.0\" |\t 6.6\" |\n| S240422ed_X161 | 08h 26m 34.51s | -21d 01' 50.6\" |\t 5.9\" |\n| S240422ed_X162 | 08h 25m 20.03s | -20d 21' 21.4\" |\t 6.0\" |\n| S240422ed_X163 | 08h 25m 18.09s | -20d 15' 06.5\" |\t 5.8\" |\n| S240422ed_X164 | 08h 24m 32.58s | -20d 14' 53.8\" |\t 6.8\" |\n| S240422ed_X165 | 08h 25m 50.04s | -20d 59' 25.8\" |\t 5.1\" |\n| S240422ed_X166 | 08h 26m 08.36s | -20d 58' 38.7\" |\t 6.1\" |\n| S240422ed_X167 | 08h 26m 17.04s | -20d 58' 15.6\" |\t 6.3\" |\n| S240422ed_X168 | 08h 25m 34.66s | -20d 18' 29.5\" |\t 5.9\" |\n| S240422ed_X169 | 08h 24m 57.04s | -20d 26' 50.5\" |\t 8.4\" |\n| S240422ed_X170 | 08h 26m 16.63s | -20d 39' 49.0\" |\t 7.1\" |\n| S240422ed_X171 | 08h 24m 52.75s | -20d 26' 15.5\" |\t 5.3\" |\n| S240422ed_X172 | 08h 08m 04.35s | -23d 24' 45.1\" |\t 8.5\" |\n| S240422ed_X173 | 08h 08m 11.03s | -23d 25' 15.4\" |\t 8.8\" |\n| S240422ed_X174 | 08h 03m 49.36s | -26d 13' 42.2\" |\t 9.3\" |\n| S240422ed_X175 | 08h 03m 28.16s | -26d 17' 32.7\" |\t 5.7\" |\n| S240422ed_X176 | 08h 03m 23.77s | -26d 19' 42.3\" |\t 5.9\" |\n| S240422ed_X177 | 08h 05m 10.86s | -25d 58' 40.0\" |\t12.0\" |\n| S240422ed_X178 | 08h 05m 32.41s | -26d 03' 59.8\" |\t 5.9\" |\n| S240422ed_X179 | 08h 04m 43.40s | -26d 03' 22.6\" |\t 5.6\" |\n| S240422ed_X180 | 08h 02m 45.33s | -26d 25' 14.7\" |\t 5.4\" |\n| S240422ed_X181 | 08h 05m 16.90s | -26d 09' 00.2\" |\t 7.3\" |\n| S240422ed_X182 | 08h 02m 58.18s | -25d 50' 21.3\" |\t 8.6\" |\n| S240422ed_X183 | 08h 03m 40.30s | -26d 03' 00.2\" |\t 6.9\" |\n| S240422ed_X184 | 08h 02m 33.85s | -26d 05' 25.7\" |\t 6.4\" |\n| S240422ed_X185 | 08h 03m 38.73s | -26d 22' 16.1\" |\t 6.2\" |\n| S240422ed_X186 | 08h 03m 05.19s | -25d 50' 21.8\" |\t 7.5\" |\n| S240422ed_X187 | 08h 05m 26.00s | -25d 57' 35.1\" |\t 7.8\" |\n| S240422ed_X188 | 08h 03m 02.65s | -25d 48' 22.2\" |\t 7.9\" |\n| S240422ed_X189 | 08h 02m 43.04s | -25d 49' 50.3\" |\t 6.4\" |\n| S240422ed_X191 | 08h 04m 42.44s | -25d 47' 20.1\" |\t 5.3\" |\n| S240422ed_X192 | 08h 03m 04.32s | -26d 27' 12.7\" |\t 6.8\" |\n| S240422ed_X193 | 08h 02m 56.44s | -26d 07' 22.2\" |\t 6.5\" |\n| S240422ed_X194 | 08h 05m 21.31s | -25d 51' 58.6\" |\t 7.5\" |\n| S240422ed_X195 | 08h 04m 26.43s | -25d 18' 43.9\" |\t 5.6\" |\n| S240422ed_X196 | 08h 04m 39.38s | -25d 50' 26.3\" |\t 6.1\" |\n| S240422ed_X197 | 08h 03m 33.96s | -25d 50' 24.0\" |\t 7.0\" |\n| S240422ed_X198 | 08h 05m 39.81s | -26d 03' 05.6\" |\t 6.0\" |\n| S240422ed_X199 | 08h 05m 24.57s | -26d 04' 33.4\" |\t 6.7\" |\n| S240422ed_X200 | 08h 05m 25.64s | -26d 03' 20.3\" |\t 6.0\" |\n| S240422ed_X201 | 08h 05m 29.95s | -26d 02' 04.2\" |\t 5.9\" |\n| S240422ed_X202 | 08h 04m 46.81s | -25d 52' 01.2\" |\t 7.1\" |\n| S240422ed_X203 | 08h 06m 04.46s | -26d 02' 57.8\" |\t 5.3\" |\n| S240422ed_X204 | 08h 04m 59.49s | -26d 05' 48.9\" |\t 7.4\" |\n| S240422ed_X205 | 08h 03m 42.53s | -26d 13' 58.9\" |\t 5.6\" |\n| S240422ed_X206 | 08h 02m 34.55s | -25d 49' 17.4\" |\t 6.3\" |\n| S240422ed_X207 | 08h 05m 12.38s | -25d 48' 58.6\" |\t 5.5\" |\n| S240422ed_X208 | 08h 02m 22.50s | -26d 24' 00.6\" |\t 6.6\" |\n| S240422ed_X209 | 08h 02m 18.98s | -25d 57' 28.4\" |\t 7.3\" |\n| S240422ed_X210 | 08h 04m 46.12s | -26d 03' 37.3\" |\t 9.4\" |\n| S240422ed_X211 | 08h 03m 16.95s | -25d 53' 01.3\" |\t 6.5\" |\n| S240422ed_X212 | 08h 03m 20.75s | -26d 11' 31.0\" |\t 6.6\" |\n| S240422ed_X213 | 08h 04m 30.57s | -25d 51' 33.7\" |\t 5.9\" |\n| S240422ed_X214 | 08h 03m 15.45s | -26d 02' 27.9\" |\t 6.0\" |\n| S240422ed_X215 | 08h 05m 11.27s | -25d 53' 49.9\" |\t 7.6\" |\n| S240422ed_X216 | 08h 01m 49.79s | -29d 38' 11.0\" |\t 7.3\" |\n| S240422ed_X217 | 08h 03m 17.43s | -27d 52' 09.5\" |\t 5.9\" |\n| S240422ed_X218 | 08h 04m 14.00s | -27d 51' 44.9\" |\t 7.6\" |\n| S240422ed_X219 | 08h 03m 37.04s | -27d 55' 52.6\" |\t 5.3\" |\n| S240422ed_X220 | 08h 03m 23.37s | -27d 46' 53.2\" |\t 6.4\" |\n| S240422ed_X221 | 08h 03m 42.72s | -27d 38' 55.6\" |\t 6.9\" |\n| S240422ed_X222 | 08h 10m 21.80s | -18d 17' 01.0\" |\t 7.0\" |\n| S240422ed_X223 | 08h 08m 49.73s | -24d 31' 22.8\" |\t 5.4\" |\n| S240422ed_X224 | 08h 02m 12.90s | -26d 23' 02.9\" |\t 5.7\" |\n| S240422ed_X225 | 08h 11m 27.69s | -18d 04' 50.0\" |\t 6.6\" |\n| S240422ed_X226 | 08h 10m 08.95s | -18d 12' 17.6\" |\t 7.3\" |\n| S240422ed_X227 | 08h 08m 55.49s | -24d 30' 23.8\" |\t 6.6\" |\n| S240422ed_X229 | 08h 03m 28.50s | -26d 24' 13.0\" |\t 5.5\" |\n| S240422ed_X230 | 08h 10m 22.31s | -18d 19' 53.3\" |\t11.8\" |\n| S240422ed_X231 | 08h 02m 48.21s | -25d 56' 51.6\" |\t 6.0\" |\n| S240422ed_X232 | 08h 10m 29.42s | -18d 12' 48.5\" |\t15.2\" |\n| S240422ed_X234 | 08h 10m 04.02s | -18d 08' 27.8\" |\t 9.0\" |\n| S240422ed_X235 | 08h 26m 17.31s | -27d 22' 40.3\" |\t16.4\" |\n| S240422ed_X236 | 08h 03m 03.62s | -26d 25' 04.6\" |\t 7.4\" |\n| S240422ed_X237 | 08h 04m 45.90s | -26d 09' 23.9\" |\t 7.6\" |\n| S240422ed_X238 | 08h 10m 30.49s | -18d 15' 43.4\" |\t 6.0\" |\n| S240422ed_X239 | 08h 05m 22.47s | -26d 01' 39.7\" |\t 5.6\" |\n| S240422ed_X240 | 08h 08m 53.52s | -24d 31' 51.8\" |\t 5.8\" |\n| S240422ed_X241 | 08h 04m 37.23s | -25d 54' 54.2\" |\t 6.2\" |\n| S240422ed_X242 | 08h 02m 58.11s | -26d 16' 58.3\" |\t 5.9\" |\n| S240422ed_X243 | 08h 05m 23.08s | -25d 59' 52.9\" |\t 6.9\" |\n| S240422ed_X244 | 08h 04m 38.78s | -26d 09' 49.1\" |\t 6.7\" |\n| S240422ed_X245 | 08h 02m 44.53s | -26d 04' 22.9\" |\t 6.7\" |\n\n\nRANK 4 sources\n==============\n\nThese are catalogued X-ray sources, showing no signs of outburst\ncompared to previous observations, so they are not likely to be related\nto the GW trigger.\n\n| Source ID\t | RA\t\t | Dec \t | Err90 |\n| S240422ed_X3 | 07h 57m 58.98s | -21d 57' 37.8\" |\t8.4\" |\n| S240422ed_X15 | 07h 58m 49.93s | -22d 00' 19.8\" |\t4.9\" |\n| S240422ed_X20 | 07h 58m 00.02s | -21d 57' 16.8\" | 12.9\" |\n| S240422ed_X102 | 08h 09m 55.15s | -24d 01' 38.6\" |\t 4.8\" |\n| S240422ed_X139 | 08h 10m 27.22s | -18d 11' 38.3\" |\t 9.0\" |\n| S240422ed_X233 | 08h 09m 03.03s | -24d 27' 11.1\" |\t 7.2\" |\n| S240422ed_X247 | 08h 09m 43.99s | -23d 58' 38.1\" |\t 8.4\" |\n| S240422ed_X248 | 08h 13m 04.13s | -29d 01' 53.2\" |\t 6.8\" |\n\nFor all flux conversions and comparisons with catalogues and upper\nlimits from other missions, we assumed a power-law spectrum with\nNH=3x10^20 cm^-2, and photon index (Gamma)=1.7, unless otherwise\nstated.\n\nThe results of the XRT automated analysis, including details of the\nsources listed above, are online at\nhttps://www.swift.ac.uk/LVC/S240422ed\n\nThis circular is an official product of the Swift XRT team.\n\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36278.",
"published": "2024-04-24T08:42:50.698741Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T08:42:50.698761Z",
"modified": "2024-04-24T08:42:50.706974Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6907,
"topic": "gcn.circular",
"uuid": "51843d29-554f-4dc9-b3da-40d041d36b23",
"title": "LIGO/Virgo/KAGRA S240422ed: MOSFIRE imaging of the DECam GW-MMADS candidate AT 2024hdm",
"submitter": "Hop gcn.circular",
"authors": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"data": {
"date": "24/04/24 09:01:56 GMT",
"from": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36279"
},
"title": "GCN CIRCULAR",
"number": "36279",
"subject": "LIGO/Virgo/KAGRA S240422ed: MOSFIRE imaging of the DECam GW-MMADS candidate AT 2024hdm"
},
"message_text": "Viraj Karambelkar (Caltech), Jacob Jencson (IPAC), Samaporn Tinyanont\n(NARIT), Mansi Kasliwal (Caltech) report on behalf of a larger\ncollaboration.\n\nWe imaged the DECam GW-MMADS source AT2024hdm (GCN 36273), reported as a\ncandidate optical counterpart to the LVK gravitational wave event S240422ed\n(GCN 36236) in the near-IR J-band with MOSFIRE on the Keck-I telescope on\nUTC 2024-04-24T07:48:25. This transient is close to a galaxy with photoz ~\n0.048 (Bilicki et al. 2014), suggesting an absolute magnitude of M_r ~ -16\nmag at discovery (GCN 36273, https://www.wis-tns.org/object/2024hdm).\n\nWe detect AT2024hdm in the J-band with m_J ~ 20.4 +/- 0.1 mag (AB). Based\non the r-band discovery magnitude, the r - J color of this transient is ~\n0.3 mag. Correcting for Galactic extinction of E(B-V) ~ 0.1 along this\ndirection gives a corrected (r-J)_corr ~ 0.15 +/- 0.1 mag, suggesting that\nthe intrinsic color is not particularly red at this phase.\n\nThis transient may be consistent with a supernova. We encourage\nspectroscopic classification to determine the true nature of the source.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36279.",
"published": "2024-04-24T09:02:13.344816Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T09:02:13.344843Z",
"modified": "2024-04-24T09:02:13.354113Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6908,
"topic": "gcn.circular",
"uuid": "efdda372-d29e-4ecd-90af-1e3bd667afe4",
"title": "LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts",
"submitter": "Hop gcn.circular",
"authors": "Dougal Dobie at University of Sydney <ddobie94@gmail.com>",
"data": {
"date": "24/04/24 10:32:21 GMT",
"from": "Dougal Dobie at University of Sydney <ddobie94@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36280"
},
"title": "GCN CIRCULAR",
"number": "36280",
"subject": "LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts"
},
"message_text": "D. Dobie, A. Gulati, T. Murphy (U. Sydney/OzGrav), J. Freeburn (Swinburne), A. Anumarlapudi, D.L. Kaplan (UWM) on behalf of a larger collaboration.\n\nWe report observations of Mag24a (GCN #36267) and the GW-MMADS source AT2024hdn (GCN #36273) with the Australia Telescope Compact Array (ATCA) on 2024-04-24 using 2x2048 MHz bands centered on 5.5 and 9 GHz.\n\nWe observed the position of Mag24a from 03:00-05:34 UTC. We chose to cease observations after independently discovering the red object at the position of the source in archival DECaPS2 data eventually reported in GCN #36274. We then observed the position of AT2024hdn from 05:35-07:40.\n\nWe do not find radio emission at the location of either optical source. After preliminary analysis of the data we report 3-sigma upper limits of\n\n| Source | Frequency (GHz) | Flux density (uJy) |\n| --------- | --------------- | ------------------ |\n| Mag24a | 5.5 | < 55 |\n| Mag24a | 9.0 | < 50 |\n| AT2024hdn | 5.5 | < 240 |\n| AT2024hdn | 9.0 | < 60 |\n\nWe thank CSIRO staff for rapidly scheduling these observations.\n\nThe Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO. We acknowledge the Gomeroi people as the Traditional Owners of the Observatory site.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36280.",
"published": "2024-04-24T10:32:38.106248Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T10:32:38.106262Z",
"modified": "2024-04-24T10:32:38.114945Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6909,
"topic": "gcn.circular",
"uuid": "713bc7fa-e270-490e-9847-985a7c6eeb93",
"title": "LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn",
"submitter": "Hop gcn.circular",
"authors": "Mansi Kasliwal at Caltech <mansikasliwal@gmail.com>",
"data": {
"date": "24/04/24 10:36:31 GMT",
"from": "Mansi Kasliwal at Caltech <mansikasliwal@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36281"
},
"title": "GCN CIRCULAR",
"number": "36281",
"subject": "LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn"
},
"message_text": "Samaporn Tinyanont (NARIT), Jesper Sollerman (OKC), Jacob Jencson (IPAC), Viraj Karambelkar (Caltech), Michael Lundquist (WMKO) and Mansi Kasliwal (Caltech)\n\nreport on behalf of a larger collaboration\n\nWe obtained a near-infrared spectrum of the DECam GW-MMADS source AT2024hdn (GCN 36273), reported as a candidate optical counterpart to the LVK gravitational wave event S240422ed (GCN 36236) in the near-IR y-band with MOSFIRE on the Keck-I telescope on UTC 2024-04-24. The signal-to-noise on the transient is low and analysis is underway. In the reduced 2D spectrum, offset from the transient location, we note two prominent emisson lines at approx. 10161 Angstrom and 10679 Angstrom from the possible star formation knot / background galaxy north of the putative host. If these two lines are [SIII], this corresponds to a galaxy redshift of z=0.12 (significantly higher than the photometric redshift estimate of 0.079 from Bilicki et al. 2014). If this knot is at the same redshift as the transient, it would imply that AT 2024hdn has an absolute magnitude that is consistent with a supernova. We thank the WMKO staff and Keck I scheduled observers for their co-operation with these Target of Opportunity observations.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36281.",
"published": "2024-04-24T10:36:42.441703Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T10:36:42.441716Z",
"modified": "2024-04-24T10:36:42.448160Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6910,
"topic": "gcn.circular",
"uuid": "b3af2b79-6c39-402d-ab47-ff65ce7517ba",
"title": "LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam",
"submitter": "Hop gcn.circular",
"authors": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
"data": {
"date": "24/04/24 13:14:11 GMT",
"from": "EP Team at NAOC/CAS <ep_ta@bao.ac.cn>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36282"
},
"title": "GCN CIRCULAR",
"number": "36282",
"subject": "LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam"
},
"message_text": "H. N. Yang, Y. L. Wang, W. J. Zhang, X. Pan, X. P. Xu, C. C. Jin, D. Y. Li, H. Sun, Y. Liu, Z. X. Ling, C. Zhang, W. Chen, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, J. J. Jin, T. Y. Lian, H. Y. Liu, M. J. Liu, Z. Z. Lv, X. Mao, H. W. Pan, W. X. Wang, Q. Y. Wu, Y. F. Xu, W. Yuan, M. Zhang, W. D. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Q. C. Shui (IHEP, CAS), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA), on behalf of the Einstein Probe team \n\nWe report on the X-ray upper limits from the ongoing observations of the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, for the potential electromagnetic counterparts reported by Swift (Evans et al. GCN 36278) and DECam (Hu et al. GCN 36273). \n\nThrough our preliminary analysis of the WXT data, we found no significant X-ray counterparts at the positions of these sources, except for AT 2024hdq which is associated with a known Seyfert I galaxy LEDA 86073. The detected flux of this Seyfert by EP-WXT is around 2 x 10^-12 erg/s/cm2, consistent with the flux given in eRASS1. Upper limits for the other sources in 0.5-4 keV at the 90% confidence level are derived from the accumulated exposure from 2024-04-23 00:37:26 (UTC) to 2024-04-23 23:48:09 (UTC).\n\nThe flux upper limits at the 90% confidence level are detailed as follows. \nSource | R.A | Dec. | Exposure (s) | Upper limit (erg/s/cm2) \n----------------------------------------------------------------------------------\nAT 2024hdk | 130.625724 | -15.59953 | 20735 | 6.4 x 10^-12\nAT 2024hdn | 127.302473 | -21.50639 | 27013 | 5.6 x 10^-12\nAT 2024hdm | 126.65801 | -20.83375 | 26785 | 5.6 x 10^-12\nAT 2024hdl | 125.472700 | -30.10220 | 39700 | 4.6 x 10^-12\nAT 2024hdo | 120.866797 | -26.01212 | 50042 | 4.1 x 10^-12\nAT 2024hdr | 120.804560 | -24.33268 | 39477 | 4.6 x 10^-12\nAT 2024hdp | 120.543455 | -27.25787 | 42801 | 4.4 x 10^-12\nS240422ed_X101 | 122.3954 | -24.3272 | 44192 | 4.4 x 10^-12\nS240422ed_X190 | 121.2770 | -26.1203 | 48919 | 4.1 x 10^-12\n----------------------------------------------------------------------------------\nNote: the X-ray upper limit from EP-WXT for another potential electromagnetic counterpart of Swift, i.e. S240422ed_X61 has been given in our previous report (GCN 36270). \n\nFollow-up observations with the Follow-up X-ray Telescope (FXT) of EP for the potential optical counterparts found by DECam have been carried out. For the two potential electromagnetic counterparts of Swift (S240422ed_X101, S240422ed_X190), we have also triggered quick follow-up observations with EP-FXT. Further results will be reported after the data analysis is completed.\n\nThe above observations were made with the WXT instrument during the commissioning phase of EP. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36282.",
"published": "2024-04-24T13:14:27.541515Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T13:14:27.541532Z",
"modified": "2024-04-24T13:14:27.550277Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6911,
"topic": "gcn.circular",
"uuid": "e16d2b6b-c8a8-4283-a156-ba9d34041b61",
"title": "IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event",
"submitter": "Hop gcn.circular",
"authors": "A. Zegarelli at Ruhr University Bochum <azegarelli@icecube.wisc.edu>",
"data": {
"date": "24/04/24 14:00:19 GMT",
"from": "A. Zegarelli at Ruhr University Bochum <azegarelli@icecube.wisc.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36283"
},
"title": "GCN CIRCULAR",
"number": "36283",
"subject": "IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event"
},
"message_text": "The IceCube Collaboration (http://icecube.wisc.edu/) reports:\n\nOn 2024-04-24 at 01:49:26.0 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_GOLD alert stream. The average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 1.225 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.\n\nAfter the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/139315_50057906.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:\n\nDate: 2024-04-24\nTime: 01:49:26.0 UT\nRA: 327.08 (+2.06, -1.70 deg 90% PSF containment) J2000\nDec: 3.06 (+1.37, -1.33 deg 90% PSF containment) J2000\n\nWe encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.\n\nTwo Fermi-LAT sources (listed in the 4FGL-DR4 or 3FHL catalogs) are located in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J2149.6+0323 (J2149.8+0322 in the 3FHL catalog) at RA: 327.42 deg and DEC: 3.40 deg (0.5 deg away from the best-fit position). The second one is 4FGL J2146.8+0425 at RA: 326.71 deg and DEC: 4.43 deg, 1.4 deg away from the best-fit position. The former source is associated with a BL Lac object, while the latter is a blazar candidate of uncertain type.\n\nAdditionally, we note that a recent GRB triggered by the Swift Burst Alert Catalog (BAT) on April 19, 2024 (GRB 240419B, detection time 2024-04-19 12:22:52 UT, GCN Circular #36180), is contained within the 90% uncertainty region of the neutrino candidate event, ~1.7 deg from its best-fit position.\n\nThe IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36283.",
"published": "2024-04-24T14:00:36.751875Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T14:00:36.751891Z",
"modified": "2024-04-24T14:00:36.760948Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6913,
"topic": "gcn.circular",
"uuid": "69ad9bff-a4ae-4e51-bfc8-fadb26eab43a",
"title": "LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations",
"submitter": "Hop gcn.circular",
"authors": "Cristina Andrade at UMN <andra104@umn.edu>",
"data": {
"date": "24/04/24 15:45:43 GMT",
"from": "Cristina Andrade at UMN <andra104@umn.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36284"
},
"title": "GCN CIRCULAR",
"number": "36284",
"subject": "LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations"
},
"message_text": "C. Andrade (UMN), P. Gokuldass (ERAU), A. Klotz (Les Makes/T60), M. Masek (FZU), Y. Rajabov (UBAI), S. Karpov (FZU), M. Prouza (FZU),\nS. Antier (OCA), M. Coughlin (UMN), P. Hello (IJCLAB), I. Tosta e Melo (UniCT-DFA), D. Turpin (CEA-Saclay/Irfu), T. Pradier(Unistra/IPHC),\nP.A Duverne (APC), N. Guessoum (AUS)\n\nReport on behalf of the GRANDMA collaboration:\n\nWe performed tiled observations of LIGO/VIRGO event S240422ed (GCN 36236, 36240, and 36243) with the\nFRAM-Auger (30cm ODK + CCD MII G4-16000, 60' x 60' field of view, Pierre Auger Observatory, Malargue, Argentina) telescope.\n\nObservations were conducted from 2024-04-23 00:02:54 to 2024-04-23 05:16:49, beginning approximately 2.46 hr after the GW trigger time, under moderate weather conditions. Using the Bilby skymap as a reference, we searched 11.5% (65.1 sq deg) of the localization region, acquiring 2 consecutive 2-minute long exposures in Johnson R filter at the individual pointings as described below:\n\n+------------+--------------+--------+---------+-------------+-------------+\n| Date | Time (UTC) | Filter | Exposure | RA | Dec |\n|------------+--------------+--------+---------+-------------+-------------+\n| 2024-04-23 | 00:02:54.252 | R | 120.0 | 125.79545 | -18.0 |\n| 2024-04-23 | 00:05:05.859 | R | 120.0 | 125.79545 | -18.0 |\n| 2024-04-23 | 00:07:27.154 | R | 120.0 | 126.81818 | -18.0 |\n| 2024-04-23 | 00:09:38.735 | R | 120.0 | 126.81818 | -18.0 |\n| 2024-04-23 | 00:12:02.014 | R | 120.0 | 126.51429 | -18.97297 |\n| 2024-04-23 | 00:14:13.631 | R | 120.0 | 126.51429 | -18.97297 |\n| 2024-04-23 | 00:16:36.403 | R | 120.0 | 126.40449 | -16.05405 |\n| 2024-04-23 | 00:18:48.019 | R | 120.0 | 126.40449 | -16.05405 |\n| 2024-04-23 | 00:21:10.954 | R | 120.0 | 127.11864 | -17.02703 |\n| 2024-04-23 | 00:23:22.559 | R | 120.0 | 127.11864 | -17.02703 |\n| 2024-04-23 | 00:25:45.930 | R | 120.0 | 124.38202 | -16.05405 |\n| 2024-04-23 | 00:27:57.467 | R | 120.0 | 124.38202 | -16.05405 |\n| 2024-04-23 | 00:30:20.097 | R | 120.0 | 127.84091 | -18.0 |\n| 2024-04-23 | 00:32:31.677 | R | 120.0 | 127.84091 | -18.0 |\n| 2024-04-23 | 00:34:51.547 | R | 120.0 | 127.41573 | -16.05405 |\n| 2024-04-23 | 00:37:03.099 | R | 120.0 | 127.41573 | -16.05405 |\n| 2024-04-23 | 00:39:22.111 | R | 120.0 | 125.08475 | -17.02703 |\n| 2024-04-23 | 00:41:33.743 | R | 120.0 | 125.08475 | -17.02703 |\n| 2024-04-23 | 00:43:52.683 | R | 120.0 | 126.10169 | -17.02703 |\n| 2024-04-23 | 00:46:04.298 | R | 120.0 | 126.10169 | -17.02703 |\n| 2024-04-23 | 00:48:26.997 | R | 120.0 | 127.54286 | -18.97297 |\n| 2024-04-23 | 00:50:38.607 | R | 120.0 | 127.54286 | -18.97297 |\n| 2024-04-23 | 00:53:01.805 | R | 120.0 | 128.42697 | -16.05405 |\n| 2024-04-23 | 00:55:13.343 | R | 120.0 | 128.42697 | -16.05405 |\n| 2024-04-23 | 00:57:34.624 | R | 120.0 | 127.24138 | -19.94595 |\n| 2024-04-23 | 00:59:46.236 | R | 120.0 | 127.24138 | -19.94595 |\n| 2024-04-23 | 01:02:06.232 | R | 120.0 | 125.39326 | -16.05405 |\n| 2024-04-23 | 01:04:17.814 | R | 120.0 | 125.39326 | -16.05405 |\n| 2024-04-23 | 01:06:37.756 | R | 120.0 | 124.77273 | -18.0 |\n| 2024-04-23 | 01:08:49.323 | R | 120.0 | 124.77273 | -18.0 |\n| 2024-04-23 | 01:11:10.415 | R | 120.0 | 127.7095 | -15.08108 |\n| 2024-04-23 | 01:13:22.008 | R | 120.0 | 127.7095 | -15.08108 |\n| 2024-04-23 | 01:15:45.628 | R | 120.0 | 126.70391 | -15.08108 |\n| 2024-04-23 | 01:17:57.217 | R | 120.0 | 126.70391 | -15.08108 |\n| 2024-04-23 | 01:20:17.265 | R | 120.0 | 127.35376 | -14.10811 |\n| 2024-04-23 | 01:22:28.875 | R | 120.0 | 127.35376 | -14.10811 |\n| 2024-04-23 | 01:24:50.113 | R | 120.0 | 126.2069 | -19.94595 |\n| 2024-04-23 | 01:27:01.724 | R | 120.0 | 126.2069 | -19.94595 |\n| 2024-04-23 | 01:29:22.108 | R | 120.0 | 128.13559 | -17.02703 |\n| 2024-04-23 | 01:31:33.663 | R | 120.0 | 128.13559 | -17.02703 |\n| 2024-04-23 | 01:40:09.688 | R | 120.0 | 126.93642 | -20.91892 |\n| 2024-04-23 | 01:42:21.259 | R | 120.0 | 126.93642 | -20.91892 |\n| 2024-04-23 | 01:44:45.889 | R | 120.0 | 128.35655 | -14.10811 |\n| 2024-04-23 | 01:46:57.480 | R | 120.0 | 128.35655 | -14.10811 |\n| 2024-04-23 | 01:49:29.976 | R | 120.0 | 125.69832 | -15.08108 |\n| 2024-04-23 | 01:51:41.523 | R | 120.0 | 125.69832 | -15.08108 |\n| 2024-04-23 | 01:54:02.080 | R | 120.0 | 123.68715 | -15.08108 |\n| 2024-04-23 | 01:56:13.674 | R | 120.0 | 123.68715 | -15.08108 |\n| 2024-04-23 | 01:58:37.600 | R | 120.0 | 125.48571 | -18.97297 |\n| 2024-04-23 | 02:00:49.167 | R | 120.0 | 125.48571 | -18.97297 |\n| 2024-04-23 | 02:03:13.104 | R | 120.0 | 124.0678 | -17.02703 |\n| 2024-04-23 | 02:05:24.705 | R | 120.0 | 124.0678 | -17.02703 |\n| 2024-04-23 | 02:07:49.310 | R | 120.0 | 128.71508 | -15.08108 |\n| 2024-04-23 | 02:10:00.873 | R | 120.0 | 128.71508 | -15.08108 |\n| 2024-04-23 | 02:12:19.642 | R | 120.0 | 127.64543 | -13.13514 |\n| 2024-04-23 | 02:14:31.240 | R | 120.0 | 127.64543 | -13.13514 |\n| 2024-04-23 | 02:16:51.118 | R | 120.0 | 126.35097 | -14.10811 |\n| 2024-04-23 | 02:19:02.679 | R | 120.0 | 126.35097 | -14.10811 |\n| 2024-04-23 | 02:21:26.549 | R | 120.0 | 127.97688 | -20.91892 |\n| 2024-04-23 | 02:23:38.143 | R | 120.0 | 127.97688 | -20.91892 |\n| 2024-04-23 | 02:26:03.066 | R | 120.0 | 128.86364 | -18.0 |\n| 2024-04-23 | 02:28:14.659 | R | 120.0 | 128.86364 | -18.0 |\n| 2024-04-23 | 02:30:36.400 | R | 120.0 | 124.69274 | -15.08108 |\n| 2024-04-23 | 02:32:48.004 | R | 120.0 | 124.69274 | -15.08108 |\n| 2024-04-23 | 02:35:10.945 | R | 120.0 | 125.34819 | -14.10811 |\n| 2024-04-23 | 02:37:22.567 | R | 120.0 | 125.34819 | -14.10811 |\n| 2024-04-23 | 02:39:46.984 | R | 120.0 | 128.27586 | -19.94595 |\n| 2024-04-23 | 02:41:58.649 | R | 120.0 | 128.27586 | -19.94595 |\n| 2024-04-23 | 02:44:23.686 | R | 120.0 | 123.37079 | -16.05405 |\n| 2024-04-23 | 02:46:35.316 | R | 120.0 | 123.37079 | -16.05405 |\n| 2024-04-23 | 02:48:57.258 | R | 120.0 | 123.34262 | -14.10811 |\n| 2024-04-23 | 02:51:08.875 | R | 120.0 | 123.34262 | -14.10811 |\n| 2024-04-23 | 02:53:32.133 | R | 120.0 | 129.15254 | -17.02703 |\n| 2024-04-23 | 02:55:43.756 | R | 120.0 | 129.15254 | -17.02703 |\n| 2024-04-23 | 02:58:05.908 | R | 120.0 | 128.57143 | -18.97297 |\n| 2024-04-23 | 03:00:17.452 | R | 120.0 | 128.57143 | -18.97297 |\n| 2024-04-23 | 03:02:40.433 | R | 120.0 | 128.64266 | -13.13514 |\n| 2024-04-23 | 03:04:52.081 | R | 120.0 | 128.64266 | -13.13514 |\n| 2024-04-23 | 03:07:14.331 | R | 120.0 | 126.6482 | -13.13514 |\n| 2024-04-23 | 03:09:25.895 | R | 120.0 | 126.6482 | -13.13514 |\n| 2024-04-23 | 03:11:49.170 | R | 120.0 | 129.35933 | -14.10811 |\n| 2024-04-23 | 03:14:00.841 | R | 120.0 | 129.35933 | -14.10811 |\n| 2024-04-23 | 03:16:21.686 | R | 120.0 | 129.4382 | -16.05405 |\n| 2024-04-23 | 03:18:33.310 | R | 120.0 | 129.4382 | -16.05405 |\n| 2024-04-23 | 03:21:04.900 | R | 120.0 | 124.3454 | -14.10811 |\n| 2024-04-23 | 03:23:16.484 | R | 120.0 | 124.3454 | -14.10811 |\n| 2024-04-23 | 03:25:38.595 | R | 120.0 | 127.29282 | -12.16216 |\n| 2024-04-23 | 03:27:50.170 | R | 120.0 | 127.29282 | -12.16216 |\n| 2024-04-23 | 03:30:14.245 | R | 120.0 | 127.67442 | -21.89189 |\n| 2024-04-23 | 03:32:25.803 | R | 120.0 | 127.67442 | -21.89189 |\n| 2024-04-23 | 03:34:49.897 | R | 120.0 | 129.63989 | -13.13514 |\n| 2024-04-23 | 03:37:01.519 | R | 120.0 | 129.63989 | -13.13514 |\n| 2024-04-23 | 03:39:23.962 | R | 120.0 | 129.72067 | -15.08108 |\n| 2024-04-23 | 03:41:35.580 | R | 120.0 | 129.72067 | -15.08108 |\n| 2024-04-23 | 03:44:00.564 | R | 120.0 | 128.28729 | -12.16216 |\n| 2024-04-23 | 03:46:12.151 | R | 120.0 | 128.28729 | -12.16216 |\n| 2024-04-23 | 03:48:34.757 | R | 120.0 | 125.65097 | -13.13514 |\n| 2024-04-23 | 03:50:46.322 | R | 120.0 | 125.65097 | -13.13514 |\n| 2024-04-23 | 03:53:08.426 | R | 120.0 | 124.65374 | -13.13514 |\n| 2024-04-23 | 03:55:19.996 | R | 120.0 | 124.65374 | -13.13514 |\n| 2024-04-23 | 03:57:43.547 | R | 120.0 | 130.36212 | -14.10811 |\n| 2024-04-23 | 03:59:55.102 | R | 120.0 | 130.36212 | -14.10811 |\n| 2024-04-23 | 04:02:18.466 | R | 120.0 | 129.01734 | -20.91892 |\n| 2024-04-23 | 04:04:30.035 | R | 120.0 | 129.01734 | -20.91892 |\n| 2024-04-23 | 04:06:53.404 | R | 120.0 | 122.33983 | -14.10811 |\n| 2024-04-23 | 04:09:05.024 | R | 120.0 | 122.33983 | -14.10811 |\n| 2024-04-23 | 04:11:26.495 | R | 120.0 | 129.28177 | -12.16216 |\n| 2024-04-23 | 04:13:38.099 | R | 120.0 | 129.28177 | -12.16216 |\n| 2024-04-23 | 04:16:01.140 | R | 120.0 | 123.65651 | -13.13514 |\n| 2024-04-23 | 04:18:12.733 | R | 120.0 | 123.65651 | -13.13514 |\n| 2024-04-23 | 04:20:34.944 | R | 120.0 | 129.6 | -18.97297 |\n| 2024-04-23 | 04:22:46.596 | R | 120.0 | 129.6 | -18.97297 |\n| 2024-04-23 | 04:25:06.802 | R | 120.0 | 129.31034 | -19.94595 |\n| 2024-04-23 | 04:27:18.396 | R | 120.0 | 129.31034 | -19.94595 |\n| 2024-04-23 | 04:29:41.406 | R | 120.0 | 130.44944 | -16.05405 |\n| 2024-04-23 | 04:31:52.989 | R | 120.0 | 130.44944 | -16.05405 |\n| 2024-04-23 | 04:34:14.611 | R | 120.0 | 128.72093 | -21.89189 |\n| 2024-04-23 | 04:36:26.183 | R | 120.0 | 128.72093 | -21.89189 |\n| 2024-04-23 | 04:38:48.313 | R | 120.0 | 129.88636 | -18.0 |\n| 2024-04-23 | 04:40:59.927 | R | 120.0 | 129.88636 | -18.0 |\n| 2024-04-23 | 04:49:43.474 | R | 120.0 | 130.63712 | -13.13514 |\n| 2024-04-23 | 04:51:55.061 | R | 120.0 | 130.63712 | -13.13514 |\n| 2024-04-23 | 04:54:16.280 | R | 120.0 | 130.16949 | -17.02703 |\n| 2024-04-23 | 04:58:49.683 | R | 120.0 | 130.72626 | -15.08108 |\n| 2024-04-23 | 04:56:27.984 | R | 120.0 | 130.16949 | -17.02703 |\n| 2024-04-23 | 05:01:01.293 | R | 120.0 | 130.72626 | -15.08108 |\n| 2024-04-23 | 05:03:26.082 | R | 120.0 | 128.79765 | -22.86486 |\n| 2024-04-23 | 05:05:37.654 | R | 120.0 | 128.79765 | -22.86486 |\n| 2024-04-23 | 05:07:59.985 | R | 120.0 | 129.85337 | -22.86486 |\n| 2024-04-23 | 05:10:11.541 | R | 120.0 | 129.85337 | -22.86486 |\n| 2024-04-23 | 05:12:32.981 | R | 120.0 | 129.55752 | -23.83784 |\n| 2024-04-23 | 05:14:44.597 | R | 120.0 | 129.55752 | -23.83784 |\n+------------+--------------+--------+---------+-------------+-------------+\n\nOur low latency analysis did not reveal any significant candidate down to the R>16.7 (5 sigma, AB system) limit.\n\nGRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger\nAddicts) is a network of robotic telescopes connected all over the\nworld with both photometry and spectrometry capabilities for Time-\ndomain Astronomy (https://grandma.lal.in2p3.fr/) Details on the FRAM\ntelescopes are available on the GRANDMA web pages or on\nhttps://grandma.ijclab.in2p3.fr/fram/\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36284.",
"published": "2024-04-24T15:45:58.417578Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T15:45:58.417590Z",
"modified": "2024-04-24T15:45:58.428901Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6914,
"topic": "gcn.circular",
"uuid": "6232d254-0c29-464b-bd6a-4575818dc111",
"title": "LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure",
"submitter": "Hop gcn.circular",
"authors": "Jillian Rastinejad at Northwestern Univ. <jillianrastinejad2024@u.northwestern.edu>",
"data": {
"date": "24/04/24 16:01:50 GMT",
"from": "Jillian Rastinejad at Northwestern Univ. <jillianrastinejad2024@u.northwestern.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36285"
},
"title": "GCN CIRCULAR",
"number": "36285",
"subject": "LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure"
},
"message_text": "Jillian C. Rastinejad (NU), David J. Sand (UA), Griffin Hosseinzadeh (UA), Charles D. Kilpatrick (NU), Wen-fai Fong (NU), Manisha Shrestha (UA), Jennifer E. Andrews (Gemini), K. Azalee Bostroem (UA), Philip N. Daly (UA), Michael J. Lundquist (Keck), Kerry Paterson (MPIA), Jeniveve Pearson (UA), Samuel D. Wyatt (GSFC) report:\n\nWe performed a vetting analysis of the candidates reported from the DECam GW-MMADS follow-up (Hu et al. 2024, GCN 36273). Following the methods outlined in Rastinejad et al. (2022) and Hosseinzadeh et al. (2024), we crossmatch each candidate with the TNS (Gal-Yam 2021) and point source catalogs (Tachibana and Miller 2018; Jayasinghe et al. 2019; Flesch et al. 2021; Gaia Collaboration 2023), search public ZTF photometry (Bellm et al. 2019), and run ATLAS forced photometry (Shingles et al. 2021) at the position of the candidate to rule out transients unrelated to the GW event. We determine a most likely host galaxy using the probability of chance coincidence method (Pcc; Bloom et al. 2002) and search for an associated spectroscopic or photometric redshift in public galaxy catalogs (White et al. 2011; Alam et al. 2015; Beck et al. 2016, 2021; Dalya et al. 2021; DESI Collaboration et al. 2023).\n\nCandidate | Vetting result\nââââââââââââââââââââââââââââââââââ\nAT2024hdk | Three marginal (~3-sigma) ATLAS forced photometry\n | detections ~3-5 days prior to GW event.\nAT2024hdl | Marginal (~4-sigma) ATLAS forced photometry detection ~4\n | days prior to GW event.\nAT2024hdm | Marginal (<5-sigma) ATLAS forced photometry detections ~2\n | months to 4 days prior to GW event.\nAT2024hdn | Five ATLAS forced photometry detections ~4-24 days prior to\n | GW event.\nAT2024hdo | Associated (Pcc = 0.002) with host galaxy\n | WISEJ080327.75-260039.2 from GLADE at z = 0.09 +/- 0.02\n | (photometric redshift; D = 404 Mpc).\nAT2024hdp | Associated (Pcc < 0.001) with host galaxy\n | WISEJ080210.31-271529.7 from GLADE at z = 0.09 +/- 0.02\n | (photometric redshift; D = 411 Mpc). ATLAS forced\n | photometry detections ~3-18 days prior to GW event.\nAT2024hdq | ZTF detections indicate periodic behavior since 2022.\nAT2024hdr | ZTF detections in 2021-2022. ATLAS forced photometry\n | detections extending >200 days prior to GW event.\n\nOverall, we determine that AT2024hdq and AT2024hdr are unrelated to S240422ed. We find candidates AT2024hdn, AT2024hdm, AT2024hdk, AT2024hdl and AT2024hdp to be likely unrelated to the GW event based on detections prior to the GW event, though we note the significance of the detections varies. In particular, combined with previously reported color and spectroscopic information, we strongly disfavor AT2024hdn and AT2024hdm as the counterparts of S240422ed (Tinyanont et al. 2024, GCN 36281; Karambelkar et al. 2024, GCN 36279). Finally, for AT2024hdo, while the most probable host galaxy photometric redshift is inconsistent with the GW-inferred distance, we cannot rule it out as a possible counterpart given large uncertainties in photometric redshift estimates in the Local Universe.\n\nSAGUARO stands for Searches After Gravitational-waves Using ARizona's Observatories (Hosseinzadeh et al. 2024). It is a partnership between the University of Arizona and Northwestern University.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36285.",
"published": "2024-04-24T16:02:08.911519Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T16:02:08.911534Z",
"modified": "2024-04-24T16:02:08.922845Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6915,
"topic": "gcn.circular",
"uuid": "7d22fd2c-a514-4bca-b451-2a3fee0578f5",
"title": "LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations",
"submitter": "Hop gcn.circular",
"authors": "Hugo Ayala at Pennsylvania State University <hgayala@psu.edu>",
"data": {
"date": "24/04/24 16:02:42 GMT",
"from": "Hugo Ayala at Pennsylvania State University <hgayala@psu.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36286"
},
"title": "GCN CIRCULAR",
"number": "36286",
"subject": "LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations"
},
"message_text": "The HAWC Collaboration (https://www.hawc-observatory.org) reports:\n\nThe HAWC Collaboration performed a follow-up of the gravitational wave\ntrigger S240422ed (GCN 36236). At the time of the trigger the HAWC\nlocal zenith was oriented towards (RA, Dec) = (77.6 deg, 19.0 deg).\n36% of the GW candidate sky location probability fell within our\nobservable field of view (0-45 deg zenith angle).\n\nWe performed a search for a short timescale emission using 6 sliding\ntime windows (dt = 0.3s, 1s, 3s, 10s, 30s and 100s), shifted forward\nin time by 20% of their width. We searched the 95% probability\ncontainment area in a timescale-dependent time period, from t0-5dt to\nt0+10dt, where t0 is the time of the GW trigger.\n\nNo significant gamma-ray detection above the background was observed.\n\nThe sensitivity of this analysis is greatly dependent on zenith angle,\nranging from 49.8deg to 60deg for the area searched in this\nanalysis. The 5sigma detection sensitivity to a 1s (100s) burst in the\n80-800GeV energy range goes from 9.9e-5 erg/cm^2 to 4.4e-4 erg/cm^2\n(5.6e-4 erg/cm^2 to 2.5e-03 erg/cm^2), depending on the zenith\nangle.\n\nA list of some of the hotspots found in the search is shown below. We found\nthat one of the galaxies that are mentioned in GCN 36235 is close \nto one of the observed hotspots. \nNo hotspot was close to the updated list in GCN 36243.\nWe mark with a â>â the hotspots that still show up in the updated localization\nof the GW (GCN 36240). \n\nTimescale 3 seconds\n RA Dec Unc. TS Galaxy\n 126.21 -8.61 0.83 10.97\n> 126.91 -16.10 0.85 11.47\n\nTimescale 10 seconds\n RA Dec Unc. TS Galaxy\n 124.80 -9.97 0.49 12.31\n> 126.65 -16.49 0.71 9.27\n\nTimescale 30 seconds\n RA Dec Unc. TS Galaxy\n 124.80 -9.97 0.49 9.01\n> 127.53 -15.71 0.64 9.15\n\nTimescale 100 seconds\n RA Dec Unc. TS Galaxy\n 110.65 -27.95 0.50 9.23\n 113.99 -20.42 0.37 10.23\n 114.08 -19.87 0.50 9.29\n 114.26 -21.94 0.52 11.29\n 120.94 -13.32 0.59 13.33 WISEA J080028.14-134847.4 (0.95deg)\n 128.23 -10.20 0.39 12.79\n> 129.46 -16.49 0.55 12.06\n\nHAWC is a TeV gamma ray water Cherenkov array located in the state of\nPuebla, Mexico. It is sensitive to the energy range ~0.1-100TeV, and\nmonitors 2/3 of the sky every day with an instantaneous field-of-view\nof ~2 sr.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36286.",
"published": "2024-04-24T16:02:49.104244Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T16:02:49.104258Z",
"modified": "2024-04-24T16:02:49.110645Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6916,
"topic": "gcn.circular",
"uuid": "be3c2230-6cbf-4e28-b1d1-a40d2c421d7f",
"title": "LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101",
"submitter": "Hop gcn.circular",
"authors": "Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>",
"data": {
"date": "24/04/24 19:05:49 GMT",
"from": "Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36287"
},
"title": "GCN CIRCULAR",
"number": "36287",
"subject": "LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101"
},
"message_text": "V. Swain (IITB), G. Waratkar (IITB), U. Pathak (IITB), A. Salgundi (IITB), A. Suresh (IITB), J. Basu (IIA), R.S. Teja (IIA), G. C. Anupama (IIA), S. Barway (IIA), V. Bhalerao (IITB), D.K. Sahu (IIA), A. Suryaprakash (IIA-CREST):\n\nWe observed the field of the rank 2 source S240422ed_X101 detected by Swift/XRT (Evans et al., GCN Circ. 36278) with the 2m Himalayan Chandra Telescope (HCT). The observation started at 2024-04-24T14:24:21 UT, i.e., 1.7 days after the LVK trigger (GCN Circ. 36236). We obtained multiple frames in the SDSS i' filter with different exposure times adding up to 55 minutes. Photometry was calibrated against PanSTARRS DR1 (Chambers et al., 2016).\n\nWe searched individual images as well as the stacked image but did not detect any afterglow within the Swift/XRT uncertainty circle. We obtain an upper limit of 21.8 mag (5 sigma) in our stacked image.\n\nThese observations were carried out under the ToO program HCT-2024-C1-P56. We thank the HCT staff for their support during the observations. The Indian Astronomical Observatory is operated by the Indian Institute of Astrophysics, Bengaluru, India.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36287.",
"published": "2024-04-24T19:06:05.845630Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T19:06:05.845646Z",
"modified": "2024-04-24T19:06:05.859409Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6917,
"topic": "gcn.circular",
"uuid": "ba7e2948-dd70-4a16-9741-c4c18c239ada",
"title": "LIGO/Virgo/KAGRA S240413p: DESGW DECam Follow-Up",
"submitter": "Hop gcn.circular",
"authors": "norafs@umich.edu",
"data": {
"date": "24/04/24 19:39:16 GMT",
"from": "norafs@umich.edu",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36288"
},
"title": "GCN CIRCULAR",
"number": "36288",
"subject": "LIGO/Virgo/KAGRA S240413p: DESGW DECam Follow-Up"
},
"message_text": "Nora Sherman (U. Mich.), Isaac McMahon (UZH), Elise Kesler (U. Mich.), Sean MacBride (U. Mich.), Andre Santos (CBPF), Simran Kaur(U. Mich.), Luidhy Santana-Silva (CBPF), Marcelle Soares-Santos (UZH), Clecio de Bom (CBPF), Ken Herner (FNAL), Kathy Vivas (NOIRLab)\n\n\nOn behalf of the DESGW team:\n\n\nWe report initial results of our DECam search for an optical counterpart of S240413p (LVK, GCN 36075) using DECam. Starting at 2024-04-16 00:33 UTC (~69.25hr post merger), we observed approximately the entirety of the 90% localization region provided in the updated sky map released on April 13, 2024 20:33:39 UTC.\n\n\nImages were processed by our difference imaging pipeline (Herner et al. 2020) using DES and public DECam images as templates. We employ a machine learning code (autoscan, Goldstein et al. 2015) to reject subtraction artifacts. Candidates were initially selected by requiring at least two high signal to noise detections, which were separated in time in order to reject moving objects. We also require an autoscan score of at least 0.7 on at least one of those detections, and a host redshift consistent with the LVK reported distance within three s.d. We have identified three candidates coinciding with the nuclei of known AGNs, posted below. These are of interest for AGN-driven optical emission for BBH mergers (e.g. Graham et. al 2020).\n\n\nAGN Name || RA || DEC || Band || Mag\n===============================================================================WISEA J105831.80+115457.6 164.632471 11.915976 r 21.89\n2MASS J10511539+05482488 162.814215 5.806858 i 18.99\nWISEA J105144.54+061108.0 162.935722 6.185632 i 20.32\n\n\n\nAll magnitudes reported are observed magnitudes. We encourage spectroscopic followup of these candidates.\n\nThe DECam Search & Discovery Program for Optical Signatures of Gravitational Wave Events (DESGW) is carried out by the Dark Energy Survey (DES) collaboration in partnership with wide ranging groups in the community. DESGW uses data obtained with the Dark Energy Camera (DECam), which was constructed by the DES collaboration with support from the Department of Energy and member institutions, and utilizes data as distributed by the Science Data Archive at NOAO. NOAO is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36288.",
"published": "2024-04-24T19:39:34.381496Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T19:39:34.381510Z",
"modified": "2024-04-24T19:39:34.390071Z",
"nonlocalizedevents": [
{
"event_id": "S240413p"
}
],
"targets": []
},
{
"id": 6918,
"topic": "gcn.circular",
"uuid": "f393cf90-3048-49e4-bc0a-8a92334ad843",
"title": "LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq",
"submitter": "Hop gcn.circular",
"authors": "Danielle Pieterse at Radboud U. <d.pieterse@astro.ru.nl>",
"data": {
"date": "24/04/24 21:10:06 GMT",
"from": "Danielle Pieterse at Radboud U. <d.pieterse@astro.ru.nl>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36289"
},
"title": "GCN CIRCULAR",
"number": "36289",
"subject": "LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq"
},
"message_text": "D.L.A. Pieterse (Radboud), H. Tranin (Barcelona), J. van Roestel (Amsterdam), P.J. Groot (Radboud, UCT, SAAO), P.M. Vreeswijk (Radboud), S. Bloemen (Radboud) and P.G. Jonker (Radboud) report on behalf of the BlackGEM/MeerLICHT Consortium:\n\nFollowing the DECam candidate counterparts to S240422ed reported by (Hu et al., GCN 36273), we looked at archival data of the the 0.6m BlackGEM/MeerLICHT telescope array located at the ESO La Silla, Chile and SAAO Sutherland, South Africa observatories.\n\nWe detect DECam candidates AT 2024hdr and AT 2024hdq as nuclear transients in archival 60s q-band (440-720 nm) images of BlackGEM and MeerLICHT. We therefore conclude that these are not the GW counterpart.\nNo Name night range q_mag range\n1 AT 2024hdr 2023/12/06-2024/04/23 19.0-19.5\n2 AT 2024hdq 2022/12/31-2024/12/03 18.6-19.2\n\nWe report transient limiting magnitudes for the other DECam candidates from (Hu et al., GCN 36273):\nNo Name limmag filter date-obs\n1 AT 2024hdk >19.6 i 2024-04-08 00:12:33\n2 AT 2024hdn >19.6 q 2024-04-23 21:25:02\n3 AT 2024hdm >19.9 q 2024-04-23 21:20:59\n4 AT 2024hdl >20.0 i 2024-04-17 23:46:19\n5 AT 2024hdo >20.3 q 2024-04-23 23:26:45\n6 AT 2024hdp >19.9 q 2024-04-23 19:39:27\n\nTransient candidates were extracted using the BlackBOX/ZOGY pipeline, where astrophotometric calibrations are performed using Gaia DR3 photometry and astrometry. Possible asteroids are filtered using the daily-updated lists of known asteroids from the Minor Planet Center. All magnitudes quoted are on the AB system.\n\nThe BlackGEM/MeerLICHT telescope are designed, installed and operated by a consortium of the following universities and institutions: Radboud University, Netherlands Research School for Astronomy NOVA, KU Leuven, Armagh Observatory and Planetarium, Technical University of Denmark, Hebrew University of Jerusalem, South African Astronomical Observatory, Tel Aviv University, Texas Tech University, University of Amsterdam, University of Barcelona, University of California at Davis, University of Cape Town, University of Durham, University of Hamburg, University of Manchester, University of Oxford, University of Potsdam, University of Valparaiso, University of Warwick, Weizmann Institute\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36289.",
"published": "2024-04-24T21:10:23.110094Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T21:10:23.110107Z",
"modified": "2024-04-24T21:10:23.117767Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6919,
"topic": "gcn.circular",
"uuid": "0e03ae01-cd8d-45c5-b1a4-655ccff618eb",
"title": "GRB 240422A: Glowbug gamma-ray detection",
"submitter": "Hop gcn.circular",
"authors": "C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>",
"data": {
"date": "24/04/24 21:13:46 GMT",
"from": "C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36290"
},
"title": "GCN CIRCULAR",
"number": "36290",
"subject": "GRB 240422A: Glowbug gamma-ray detection"
},
"message_text": "R. Woolf, C.C. Cheung, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report:\n \nThe Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 240422A, which was also detected by Fermi/GBM (GCN 36222).\n\nThe detection occurred during a time of high background, thus complicating the analysis. Using an adaptive window with a resolution of 32-ms, the initial peak seen in the GBM light curve was recovered, with a burst onset determined to be 2024-04-22 02:40:55.400 with a duration of 4.1 s and a total significance of about 8.0 sigma.\n\nThe analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.\n \nGlowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâs STP-H9 to the ISS. The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.\n \n[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959\n[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O\n[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006\n \nDistribution Statement A: Approved for public release. Distribution is unlimited.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36290.",
"published": "2024-04-24T21:13:54.569505Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T21:13:54.569519Z",
"modified": "2024-04-24T21:13:54.575660Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6920,
"topic": "gcn.circular",
"uuid": "032c2eae-ee1e-48ed-af72-bdfe52a93834",
"title": "GRB 240421B: Swift-BAT refined analysis",
"submitter": "Hop gcn.circular",
"authors": "Sibasish Laha at GSFC <sibasish.laha@nasa.gov>",
"data": {
"date": "24/04/24 21:46:59 GMT",
"from": "Sibasish Laha at GSFC <sibasish.laha@nasa.gov>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36291"
},
"title": "GCN CIRCULAR",
"number": "36291",
"subject": "GRB 240421B: Swift-BAT refined analysis"
},
"message_text": "S. D. Barthelmy (GSFC), H. A. Krimm (NSF),\nS. Laha (GSFC/UMBC),A. Y. Lien (U Tampa),\nC. B. Markwardt (GSFC),M. J. Moss (GSFC),\nD. M. Palmer (LANL), T. Parsotan (GSFC),\nT. Sakamoto (AGU) (i.e. the Swift-BAT team):\n\nUsing the data set from T-239 to T+963 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 240421B (trigger #1223470)\n(Williams, et al., GCN Circ. 36208). The BAT ground-calculated position is\nRA, Dec = 299.685, -14.878 deg which is\n RA(J2000) = 19h 58m 48.03s\n Dec(J2000) = -14d 51' 36.4\"\nwith an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 4%.\n\nThe BAT light curve shows a complex structure with a duration of ~ 40 sec.\nT90 (15-350 keV) is 24.00 +- 9.22 sec (estimated error including systematics).\n\nThe time-averaged spectrum from T-30.4 to T+7.6 sec is best fit by a power law\nwith an exponential cutoff. This fit gives a photon index 0.63 +- 0.52,\nand Epeak of 81.3 +- 22.3 keV (chi squared 50.17 for 56 d.o.f.). For this\nmodel the total fluence in the 15-150 keV band is 6.4 +- 0.5 x 10^-06 erg/cm2\nand the 1-sec peak flux measured from T-0.36 sec in the 15-150 keV band is\n14.1 +- 1.6 ph/cm2/sec. A fit to a simple power law gives a photon index\nof 1.55 +- 0.10 (chi squared 61.45 for 57 d.o.f.). All the quoted errors\nare at the 90% confidence level.\n\nThe results of the batgrbproduct analysis are available at\nhttps://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1223470\n\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36291.",
"published": "2024-04-24T21:47:15.925293Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T21:47:15.925328Z",
"modified": "2024-04-24T21:47:15.933443Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6921,
"topic": "gcn.circular",
"uuid": "52138e48-a7bf-4e75-bdf6-609208a7df8d",
"title": "GRB 240419B: Swift-BAT refined analysis",
"submitter": "Hop gcn.circular",
"authors": "Sibasish Laha at GSFC <sibasish.laha@nasa.gov>",
"data": {
"date": "24/04/24 21:47:33 GMT",
"from": "Sibasish Laha at GSFC <sibasish.laha@nasa.gov>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36292"
},
"title": "GCN CIRCULAR",
"number": "36292",
"subject": "GRB 240419B: Swift-BAT refined analysis"
},
"message_text": "T. Sakamoto (AGU), S. D. Barthelmy (GSFC),\nH. A. Krimm (NSF), S. Laha (GSFC/UMBC),\nA. Y. Lien (U Tampa), C. B. Markwardt (GSFC),\nM. J. Moss (GSFC), D. M. Palmer (LANL),\nT. Parsotan (GSFC),(i.e. the Swift-BAT team):\n\nUsing the data set from T-61 to T+242 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 240419B (trigger #1223072)\n(Dichiara, et al., GCN Circ. 36180). The BAT ground-calculated position is\nRA, Dec = 325.853, 4.299 deg which is\n RA(J2000) = 21h 43m 24.7s\n Dec(J2000) = +04d 17' 58.2\"\nwith an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 43%.\n\nThe BAT light curve shows a complex structure with a duration of ~ 150 sec.\nT90 (15-350 keV) is 132.16 +- 26.29 sec (estimated error including systematics).\n\nThe time-averaged spectrum from T-3.3 to T+159.5 sec is best fit by a simple\npower-law model. The power law index of the time-averaged spectrum is\n1.92 +- 0.09. The fluence in the 15-150 keV band is 4.1 +- 0.2 x 10^-06 erg/cm2.\nThe 1-sec peak photon flux measured from T+116.36 sec in the 15-150 keV band\nis 2.4 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence\nlevel.\n\nThe results of the batgrbproduct analysis are available at\nhttps://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1223072\n\n\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36292.",
"published": "2024-04-24T21:47:38.965579Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T21:47:38.965599Z",
"modified": "2024-04-24T21:47:38.973268Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6922,
"topic": "gcn.circular",
"uuid": "25c34e48-ff90-42fe-ab48-c92d6fa5e728",
"title": "LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates",
"submitter": "Hop gcn.circular",
"authors": "Arne Rau at MPE <arau@mpe.mpg.de>",
"data": {
"date": "24/04/24 23:09:41 GMT",
"from": "Arne Rau at MPE <arau@mpe.mpg.de>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36293"
},
"title": "GCN CIRCULAR",
"number": "36293",
"subject": "LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates"
},
"message_text": "Zhu Liu, Arne Rau, Chandreyee Maitra (all MPE), Lorenzo Ducci (IAAT), Mirko Krumpe, Axel Schwope (both AIP):\n\nWe report constraints on the historical X-ray emission based on archival X-ray observations from the eROSITA X-ray telescope (Predehl et al. A&A 647, A1, 2021) on board the SRG mission for the three potential electromagnetic counterparts of the LIGO/Virgo/KAGRA candidate NSBH event S240422ed (GCN 36236) detected by Swift/XRT (GCN 36278).\n\nThe three sources were within the Field-of-View of eROSITA during each of the first four eROSITA all-sky surveys (eRASS) conducted between 2019 December and 2021 December. The three sources were not detected in individual eRASS scans or in the combined eRASS data (hereafter referred to as eRASS:4). Assuming a power-law model with a photon index of 1.7 and a column density of 3.0E20 cm^-2, we derived the following X-ray flux upper limits using the eRASS:4 data (total exposure uncorrected for vignetting is approximately 800s):\n\n-----------------------------------------------------\nName | 0.3-10.0 keV | 0.2-2.3 keV | Total Exp\n | ergs/cm^2/s | ergs/cm^2/s | s\n-----------------------------------------------------\nS240422ed_X101 | < 1.2e-13 | < 5.2e-14 | 816\nS240422ed_X61 | < 7.9e-14 | < 3.4e-14 | 881\nS240422ed_X190 | < 8.2e-14 | < 3.6E-14 | 853\n-----------------------------------------------------\n\nThe Galactic neutral hydrogen column density (HI4PI map, N. Ben Bekhti et al., 2016, A&A 594, A116)) for these three sources are much higher than 3E20 cm^-2, we thus also derived the 3 sigma absorbed X-ray flux upper limits with the column density fixed at the value estimated from the HI4PI map:\n\n-------------------------------------------------------------\nName | 0.3-10.0 keV | 0.2-2.3 keV | NH | Total Exp\n | ergs/cm^2/s | ergs/cm^2/s | cm**-2 | s\n-------------------------------------------------------------\nS240422ed_X101 | < 1.8E-13 | < 5.5E-14 | 2.0E21 | 816\nS240422ed_X61 | < 1.8E-13 | < 4.1E-14 | 5.0E21 | 881\nS240422ed_X190 | < 1.3E-13 | < 3.8E-14 | 2.1E21 | 853\n-------------------------------------------------------------\n\nAll the Swift/XRT sources show significant X-ray flux increases compared to the eROSITA upper limits, suggesting that they are indeed X-ray transients.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36293.",
"published": "2024-04-24T23:09:59.245494Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-24T23:09:59.245510Z",
"modified": "2024-04-24T23:09:59.254677Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6923,
"topic": "gcn.circular",
"uuid": "ad1ce69e-4200-4d97-932b-af273937d4ef",
"title": "Fermi trigger No 735697285: Global MASTER-Net observations report",
"submitter": "Hop gcn.circular",
"authors": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"data": {
"date": "24/04/25 00:31:14 GMT",
"from": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36294"
},
"title": "GCN CIRCULAR",
"number": "36294",
"subject": "Fermi trigger No 735697285: Global MASTER-Net observations report"
},
"message_text": "V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,\nG.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij\n(Lomonosov Moscow State University, SAI, Physics Department),\n\nR. Podesta, C.Lopez, F. Podesta, C.Francile\n(Observatorio Astronomico Felix Aguilar OAFA),\n\nR. Rebolo, M. Serra\n(The Instituto de Astrofisica de Canarias),\n\nD. Buckley\n(South African Astronomical Observatory),\n\nO.A. Gress, N.M. Budnev, O.Ershova\n(Irkutsk State University, API),\n\nL.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,\nA.R.Corella, L.H.Rodriguez\n(INAOE, Guillermo Haro Astrophysics Observatory),\n\nA. Tlatov, D. Dormidontov\n(Kislovodsk Solar Station of the Pulkovo Observatory),\n\nV. Yurkov, A. Gabovich\n(Blagoveschensk Educational State University)\n\nMASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB240425.01 (trigger No 735697285,15h 01m 45.60s , +45d 39m 00.0s, R=5.8) errorbox 96 sec after notice time and 128 sec after trigger time at 2024-04-25 00:23:28 UT, with upper limit up to 13.0 mag. The observations began at zenith distance = 20 deg. The sun altitude is -21.9 deg.\n\nMASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB240425.01 errorbox 109 sec after notice time and 141 sec after trigger time at 2024-04-25 00:23:41 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 79 deg. The sun altitude is -59.1 deg.\n\nThe galactic latitude b = 58 deg., longitude l = 77 deg.\n\n\nReal time updated cover map and OT discovered available here:\nhttps://master.sai.msu.ru/site/master2/observ.php?id$34813\n\nWe obtain a following upper limits.\n\nTmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment\n_________|_____________________|_____________________|____________________________________|_____|_______|_______|________\n\n 144 | 2024-04-25 00:23:28 | MASTER-Tavrida | (15h 02m 27.12s , +45d 55m 23.3s) | C | 30 | 13.0 |\n 156 | 2024-04-25 00:23:41 | MASTER-SAAO | (15h 00m 05.69s , +45d 46m 57.7s) | C | 30 | 17.1 |\n 156 | 2024-04-25 00:23:41 | MASTER-SAAO | (15h 02m 38.82s , +45d 34m 01.6s) | C | 30 | 17.0 |\n 181 | 2024-04-25 00:24:05 | MASTER-Tavrida | (15h 02m 29.03s , +45d 57m 04.9s) | C | 30 | 12.4 |\n 206 | 2024-04-25 00:24:31 | MASTER-SAAO | (15h 00m 05.85s , +45d 47m 01.8s) | C | 30 | 17.1 |\n 206 | 2024-04-25 00:24:31 | MASTER-SAAO | (15h 02m 38.88s , +45d 34m 06.6s) | C | 30 | 17.0 |\nFilter C is a clear (unfiltred) band.\n\n\nThe observation and reduction will continue.\nThe message may be cited.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36294.",
"published": "2024-04-25T00:31:30.332614Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T00:31:30.332626Z",
"modified": "2024-04-25T00:31:30.341538Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6924,
"topic": "gcn.circular",
"uuid": "56813b0e-d80d-4ddc-a394-1c52f9354734",
"title": "GRB 240425A: Fermi GBM Final Real-time Localization",
"submitter": "Hop gcn.circular",
"authors": "Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>",
"data": {
"date": "24/04/25 00:33:16 GMT",
"from": "Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36295"
},
"title": "GCN CIRCULAR",
"number": "36295",
"subject": "GRB 240425A: Fermi GBM Final Real-time Localization"
},
"message_text": "The Fermi GBM team reports the detection of a likely LONG GRB\n\nAt 00:21:20 UT on 25 Apr 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240425A (trigger 735697285.341006 / 240425015).\n\nThe on-ground calculated location, using the Fermi GBM trigger data, is RA = 227.7, Dec = 46.7 (J2000 degrees, equivalent to J2000 15h 10m, 46d 42'), with a statistical uncertainty of 3.6 degrees.\n\nThe angle from the Fermi LAT boresight is 86.0 degrees.\n\nThe skymap can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240425015/quicklook/glg_skymap_all_bn240425015.png\n\nThe HEALPix FITS file, including the estimated localization systematic, can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240425015/quicklook/glg_healpix_all_bn240425015.fit\n\nThe GBM light curve can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240425015/quicklook/glg_lc_medres34_bn240425015.gif\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36295.",
"published": "2024-04-25T00:33:33.631067Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T00:33:33.631080Z",
"modified": "2024-04-25T00:33:33.637004Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6925,
"topic": "gcn.circular",
"uuid": "6e5c70e7-f840-487b-9689-98821acbcd54",
"title": "LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN",
"submitter": "Hop gcn.circular",
"authors": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"data": {
"date": "24/04/25 00:59:38 GMT",
"from": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36296"
},
"title": "GCN CIRCULAR",
"number": "36296",
"subject": "LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN"
},
"message_text": "A. L. Piro, J. D. Simon (Carnegie), A. Polin (Carnegie/Purdue), D. A. Coulter (STScI), M. R. Drout (Toronto), R. J. Foley, and C. Rojas-Bravo (UC Santa Cruz)\n\nreport on behalf of the Carnegie Gravitational wave ElectroMagnetic follow-up (CGEM) and the One-Meter Two-Hemisphere (1M2H) collaborations:\n\nAs part of our ongoing search for optical counterparts to the candidate gravitational wave event S240422ed using the 6.5m Magellan Clay telescope with the LDSS-3 spectrograph, we have obtained an optical spectrum of the DECam-reported counterpart candidate AT2024hdo (GCN 36273).\n\nWe obtained 2x1200s spectra of AT2024hdo and its presumed host galaxy with the VPH-All grating spanning 4000-10000A. The host galaxy has strong emission lines at z = 0.0658. Examination of the spectrum of AT2024hdo reveals broad P-Cygni H-alpha emission consistent with a Type II SN at z = 0.0658. We therefore conclude that AT2024hdo is unlikely to be associated with S240422ed.\n\nWe thank Marcelo Mora, Povilas Palunas, and the rest of the LCO staff for making these observations possible.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36296.",
"published": "2024-04-25T00:59:55.187483Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T00:59:55.187496Z",
"modified": "2024-04-25T00:59:55.195120Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6926,
"topic": "gcn.circular",
"uuid": "0ab24c18-e3de-461a-89fd-333b8906fe1f",
"title": "LIGO/Virgo/KAGRA S240422ed: ANU 2.3m followup of candidate counterparts",
"submitter": "Hop gcn.circular",
"authors": "christopher.lidman@anu.edu.au",
"data": {
"date": "24/04/25 01:50:51 GMT",
"from": "christopher.lidman@anu.edu.au",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36297"
},
"title": "GCN CIRCULAR",
"number": "36297",
"subject": "LIGO/Virgo/KAGRA S240422ed: ANU 2.3m followup of candidate counterparts"
},
"message_text": "C. Lidman, C. Wolf, C. Onken, L. Sun, S. Scott (ANU), K. Auchettl (U. Melbourne), S. Chang (Seoul National University), J. Cooke, A. Moller (Swinburne), D. Galloway (Monash), and L. Wen (UWA) report on behalf of a larger collaboration:\n\nWe report observations of the GW-MMADS sources AT2024hdr and AT2024hdl (GCN #36273) with the WiFES optical spectrograph on the ANU 2.3m telescope.\n\nA weak source is visible near the reported location of AT2024hdl.\n\nWe report on the redshifts of the likely host galaxies.\n\n| Source | Host Redshift | Comment\n| --------- | ---------------------------------------------------------------------------------------\n|\n| AT2024hdl | 0.0416 | Redshift based on weak emission line features\n| AT2024hdr | 0.0659 | AGN features\n\nThe ANU 2.3m telescope is run by the Australian National University\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36297.",
"published": "2024-04-25T01:51:05.735109Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T01:51:05.735122Z",
"modified": "2024-04-25T01:51:05.745156Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6927,
"topic": "gcn.circular",
"uuid": "cd479ea5-66cc-421d-a6e5-c9becc528db4",
"title": "LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations",
"submitter": "Hop gcn.circular",
"authors": "Tomas Cabrera <tcabrera@andrew.cmu.edu>",
"data": {
"date": "24/04/25 04:11:50 GMT",
"from": "Tomas Cabrera <tcabrera@andrew.cmu.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36298"
},
"title": "GCN CIRCULAR",
"number": "36298",
"subject": "LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations"
},
"message_text": "Tomás Cabrera (CMU), Lei Hu (CMU), Igor Andreoni (UMD), Keerthi Kunnumkai (CMU), Brendan O'Connor (CMU), Antonella Palmese (CMU), Robert Stein (Caltech), Tomás Ahumada (Caltech), Mattia Bulla (Ferrara) report on behalf of the GW-MMADS team:\n\nWe report new candidates from the DECam GW-MMADS survey program (GCN 36245, GCN 36273) follow-up of the LIGO/Virgo/KAGRA event S240422ed (GCN 36236, GCN 36240).\n\nWe ran the SFFT difference imaging (Hu et al. 2022) on images from the second night of observations (between 2024-04-23 23:15 and 2024-04-24 03:46 UTC) where archival images were available for use as templates. We filtered out likely stars, moving objects, and recent transients from the ZTF survey. We visually inspected the remaining transients.\n\nWe reported on TNS new transients within the LVK 95% CI area, and report here new candidate counterparts possibly associated with a host galaxy:\n\n+-------------------------+------------+------------+------------+---------+\n| id | tns | ra | dec | comment |\n|-------------------------+------------+------------+------------+---------+\n| C202404240825089m244346 | AT 2024hfq | 126.286902 | -24.729418 | [1] |\n| T202404230841039m183535 | AT 2024hfr | 130.266165 | -18.593131 | [2] |\n| T202404230828385m202260 | AT 2024hfs | 130.266165 | -18.593131 | |\n+-------------------------+------------+------------+------------+---------+\n\n[1] - This source is within 0.4 arcsec of the galaxy WISEA J082508.82-244345.9.\n[2] - This source is within 0.3 arcsec from the object WISEA J084103.91-183532.4. This galaxy has a 2MASS photometric redshift (Bilicki et al. 2014) of 0.049.\n\nNone of these transients shows a fast (> 0.3 mag/day) rise or fade in their light curves from preliminary photometry. GW-MMADS DECam transients reported yesterday in GCN 36273 do not show a rapid evolution (> 0.3 mag/day) in z- or r-band between the first and second night of observations.\n\nWe thank the CTIO and NOIRLab staff for supporting these observations and the data calibrations.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36298.",
"published": "2024-04-25T04:12:07.863727Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T04:12:07.863745Z",
"modified": "2024-04-25T04:12:07.871530Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6942,
"topic": "gcn.circular",
"uuid": "78e30fed-fed0-4f00-9aa6-a0921d1ab0be",
"title": "LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190",
"submitter": "Hop gcn.circular",
"authors": "Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>",
"data": {
"date": "24/04/25 15:46:41 GMT",
"from": "Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36305"
},
"title": "GCN CIRCULAR",
"number": "36305",
"subject": "LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190"
},
"message_text": "V. Swain (IITB), G. Waratkar (IITB), A. Salgundi (IITB), R. Kumar (IITB), A. Suresh (IITB), U. Pathak (IITB), V. Bhalerao (IITB), S. Wadawale (PRL), P. Neelam (PRL), K. Dhakar (PRL), A. Chakraborty (PRL):\n\nWe observed the field of the rank 2 source S240422ed_X190 detected by Swift/XRT (Evans et al., GCN Circ. 36278) with the PRL 2.5m telescope (arXiv:2401.07715). The observation started at 2024-04-24 15:00:17 UT, i.e., 1.73 days after the LVK trigger (GCN Circ. 36236). We obtained a single exposure of 40 min in the Bessel V filter. Photometric calibration was performed with respect to field stars from the NOMAD catalogue.\n\nWe did not detect any source within the Swift/XRT uncertainty circle. We obtain an upper limit of 19.9 mag (5 sigma) in our image, where the sensitivity was limited due to the high airmass of observations. This is consistent with the upper limits reported in Ducoin et al., GCN Circ. 36299.\n\nWe thank the PRL team for their support during the observation. The 2.5m telescope at the Mt. Abu observatory is operated by the Physical Research Laboratory (PRL) Ahmedabad, supported by the Department of Space, Government of India.\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36305.",
"published": "2024-04-25T15:46:57.009559Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T15:46:57.009591Z",
"modified": "2024-04-25T15:46:57.018989Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6943,
"topic": "gcn.circular",
"uuid": "326881ba-4ff4-4b67-9fb4-eeea96c90c3d",
"title": "LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations",
"submitter": "Hop gcn.circular",
"authors": "O. Guiffreda at UMD <oriogui@umd.edu>",
"data": {
"date": "24/04/25 16:12:11 GMT",
"from": "O. Guiffreda at UMD <oriogui@umd.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36306"
},
"title": "GCN CIRCULAR",
"number": "36306",
"subject": "LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations"
},
"message_text": "O. Guiffreda (UMD), J. Durbak (UMD), E. Troja (U Rome), R.Hamada (Osaka U), T, Nagano (Osaka U), A. S. Kutyrev (NASA/GSFC, UMD), D. Suzuki (Osaka U), T. Sumi (Osaka U), K. De (MIT), S. B. Cenko (NASA/GSFC),\n\nFollowing the report of the LVK gravitational wave candidate S240422ed (GCN 36236, GCN 36240), we began tiling the field in J band with PRIME. Each tile has an exposure of approximately 900 s to reach a sensitivity of J~21 AB mag. Observations began on 2023-04-23 17:01 UTC and are currently ongoing.\n\nOur pointings are reported to the TreasureMap (Wyatt et al., 2020): https://treasuremap.space/alerts?graceids=S240422ed\n\nData reduction and analysis is in progress.\n\nPRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO) (Kutyrev et al. 2023, Yama et al. 2023).\n\nWe thank the staff at SAAO for their support with these observations.\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36306.",
"published": "2024-04-25T16:12:26.581287Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T16:12:26.581306Z",
"modified": "2024-04-25T16:12:26.590275Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6944,
"topic": "gcn.circular",
"uuid": "4b259c48-3af5-4ac3-9113-168c98f54f86",
"title": "S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4",
"submitter": "Hop gcn.circular",
"authors": "Paul Groot at Radboud University Nijmegen <p.groot@astro.ru.nl>",
"data": {
"date": "24/04/25 17:01:30 GMT",
"from": "Paul Groot at Radboud University Nijmegen <p.groot@astro.ru.nl>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36307"
},
"title": "GCN CIRCULAR",
"number": "36307",
"subject": "S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4"
},
"message_text": "P.J. Groot (Radboud, UCT, SAAO), H. Tranin (Barcelona), H. Wichern\n(DTU), G. Leloudas (DTU), F. Stoppa (Radboud), I. Arcavi (Tel Aviv),\nS. Bloemen (Radboud), P.M. Vreeswijk (Radboud), D. Pieterse (Radboud)\nreport on behalf of the BlackGEM/MeerLICHT Consortium:\n\nFollowing the LVK Alert S240422ed the 0.6m BlackGEM/MeerLICHT\ntelescope array located at the ESO La Silla, Chile and SAAO\nSutherland, South Africa observatories observed the error box with the\nML1/BG2/BG4 telescopes using a predefined sky-grid tiling that covers\nthe accessible part of the error region using the ranked-tiling method\nas outlined in Ghosh et al. (2016). Observations were obtained in the\nq band, spanning 440-720nm, using a 2x10-tile strategy. Starting with\nthe highest probability tiles a set of 10-tiles was observed in the\nq-band filter using 60s exposures each, which was repeated directly\nafter the first 10 tiles were observed. Subsequently tiles 11-20 were\nobserved in the same two-visit manner, etc.\n\nObservations on the Updated error region of S240422ed (Biscoveanu et\nal., GCN Circular 36240) were repeated on the nights of 2024-04-23 and\n2024-04-24 following the same tiling pattern.\n\nTransient candidates were extracted using the BlackBOX/ZOGY pipeline,\nwhere astrophotometric calibrations are performed using Gaia DR3\nphotometry and astrometry. Possible asteroids are filtered using the\ndaily-updated lists of known asteroids from the Minor Planet\nCenter. All coordinates are given in the ICRS, epoch J2016.0\nastrometric frame and magnitudes quoted are on the AB system.\n\nNext to the MeerLICHT/BlackGEM detection of AT 2024hfx (Smith et al.,\nGCN36303; Groot et al., GCN36304) we find one more candidate that\ncannot be ruled out as the counterpart to S240422ed:\n\nName RA (ICRS) Dec(ICRS) Filter AB-Mag Date-UT\nMLTJ080628.10-250116.4 121.61711 -25.02119 q 19.92+/-0.16 2024-04-24\n17:32:29\n\"\"\t\t \"\" \"\" q 19.70+/-0.15 2024-04-24\n17:45:43\n\nThe candidate was reported to the Transient Name Server as AT2024hgl.\n\nThe last non-detection at this position with MeerLICHT was obtained on\n2022-01-28 and is therefore not constraining. Inspection of the public\nATLAS archive shows no recent brightening or flaring at the source\nlocation.\n\n\nThe BlackGEM/MeerLICHT telescopes are designed, installed and operated\nby a consortium of the following universities and institutions:\nRadboud University, Netherlands Research School for Astronomy NOVA, KU\nLeuven, Armagh Observatory and Planetarium, Hebrew University of\nJerusalem, South African Astronomical Observatory, Technical\nUniversity of Denmark, Tel Aviv University, Texas Tech University,\nUniversity of Amsterdam, University of Barcelona, University of\nCalifornia at Davis, University of Cape Town, University of Durham,\nUniversity of Hamburg, University of Manchester, University of Oxford,\nUniversity of Potsdam, University of Valparaiso, University of\nWarwick, Weizmann Institute\n\nReferences:\nGhosh et al., 2016, A&A 592, 82\n\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36307.",
"published": "2024-04-25T17:01:47.919754Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T17:01:47.919785Z",
"modified": "2024-04-25T17:01:47.933936Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6945,
"topic": "gcn.circular",
"uuid": "0d08bac4-8ad5-45dd-b2fb-4ed264ed5283",
"title": "LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations",
"submitter": "Hop gcn.circular",
"authors": "Amit Kumar at University of Warwick, UK <amitkundu515@gmail.com>",
"data": {
"date": "24/04/25 18:03:51 GMT",
"from": "Amit Kumar at University of Warwick, UK <amitkundu515@gmail.com>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36308"
},
"title": "GCN CIRCULAR",
"number": "36308",
"subject": "LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations"
},
"message_text": "D. Steeghs, K. Ackley, M. J. Dyer, J. Lyman, D. O'Neill, K. Ulaczyk; F. Jimenez-Ibarra, A. Kumar, B. Godson, T. Killestein, B. Gompertz, M. Kennedy, S. Belkin, J. Rana, D. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall; E. Palle and D. Pollacco report on behalf of the GOTO collaboration:\n\nWe report on additional optical observations and candidate vetting with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to the LIGO/Virgo/KAGRA candidate NSBH event S240422ed (The LIGO-Virgo-KAGRA Collaboration, GCN 36236).\n\nSince our initial update (Ackley et al. GCN 36257), additional passes have been made across the skymap using deeper 12x60s exposure sets. In total, 82% of the total probability region has been searched and vetted. We did not identify any additional sources of interest that can be associated with an EM counterpart to S240422ed.\n\nAT2024hfx / GOTO24aph (https://www.wis-tns.org/object/2024hfx) was detected in multiple passes, with the first GOTO detection at L = 18.4 just 5 hrs after the i = 20.1 Pan-STARRS detection reported in Smith et al. GCN 36303. This is in line with the detections reported in Groot et al. GCN 36304. The reported detections, archival ZTF detection and presence of an underlying blue source is more in line with a CV/dwarf nova event.\n\nObservation details for GOTO24aph are as follows:\n\nDate Obs Tel Exp (s) Mag Err Lim Mag Filter\n2024-04-24T11:52:37\t GOTO-S 600 18.366\t0.128 18.9 L\n2024-04-24T21:02:34\t GOTO-N 720 18.393\t0.075 \t 19.6 L\n2024-04-24T21:33:05\t GOTO-N 720 18.551\t0.059 19.8 L\n\nAT2024hgl (Groot et al., GCN 36307) ; no source is detected at this position with 5-sigma forced photometry upper limits L>19.7 for visits on both April 23 and April 25:\n\n2024-04-23T09:05:41\t GOTO-S >19.7\n2024-04-25T10:25:48\t GOTO-S >19.7\n\nGOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36308.",
"published": "2024-04-25T18:04:12.987053Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T18:04:12.987071Z",
"modified": "2024-04-25T18:04:12.995151Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6946,
"topic": "gcn.circular",
"uuid": "4bdec175-3eb5-416b-9fec-829acead2df4",
"title": "IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube",
"submitter": "Hop gcn.circular",
"authors": "Alicia Mand at IceCube/UW-Madison <aemand@wisc.edu>",
"data": {
"date": "24/04/25 20:37:57 GMT",
"from": "Alicia Mand at IceCube/UW-Madison <aemand@wisc.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36309"
},
"title": "GCN CIRCULAR",
"number": "36309",
"subject": "IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube"
},
"message_text": "The IceCube Collaboration (http://icecube.wisc.edu/) reports:\n\nIceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-240424A (https://gcn.nasa.gov/circulars/36283) in a time range of 1000 seconds centered on the alert event time (2024-04-24 01:41:06.000 UTC to 2024-04-24 01:57:46.000 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-240424A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-240424A is 1.4e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 3e+02 GeV and 2e+05 GeV.\n\nA subsequent search was performed including 2 days of data centered on the alert event time (2024-04-23 01:49:26.000 UTC to 2024-04-25 01:49:26.000 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-240424A is 1.6e-01 GeV cm^-2 in a 2 day time window.\n\nThe IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu.\n\n[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36309.",
"published": "2024-04-25T20:38:12.841519Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-25T20:38:12.841540Z",
"modified": "2024-04-25T20:38:12.850249Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6956,
"topic": "gcn.circular",
"uuid": "13976adf-2415-4da0-b265-76da458078da",
"title": "LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates",
"submitter": "Hop gcn.circular",
"authors": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"data": {
"date": "24/04/26 01:28:33 GMT",
"from": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36311"
},
"title": "GCN CIRCULAR",
"number": "36311",
"subject": "LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates"
},
"message_text": "A. L. Piro, J. D. Simon (Carnegie), A. Polin (Carnegie/Purdue), D. A. Coulter (STScI), M. R. Drout (Toronto), R. J. Foley, and C. Rojas-Bravo (UC Santa Cruz)\n\nreport on behalf of the Carnegie Gravitational wave ElectroMagnetic follow-up (CGEM) and the One-Meter Two-Hemisphere (1M2H) collaborations:\n\nAs part of our ongoing search for optical counterparts to the candidate gravitational wave event S240422ed using the 6.5m Magellan Clay telescope with the LDSS-3 imager, we have obtained optical imaging of the Swift/XRT sources S240422ed_X61 (GCN 36278, GCN 36259, GCN 36262, GCN 36271, GCN 36293), 240422ed_X101 (GCN 36278, GCN 36287, GCN 36293), and S240422ed_X190 (GCN 36278, GCN 36293, GCN 36305).\n\nBased on comparison with DECaPS2 images, we do not detect transient sources within the XRT error circle in any of these fields. We estimate the following 5-sigma limiting magnitudes:\n\n+----------------+---------------------+--------+-----------------+\n| ID | UT observation date | filter | magnitude limit |\n+----------------+---------------------+--------+-----------------+\n| S240422ed_X61 | 2024-04-24T00:40:24 | i | 23.6 |\n| S240422ed_X101 | 2024-04-25T00:30:25 | i | 23.2 |\n| S240422ed_X190 | 2024-04-25T00:33:35 | i | 23.1 |\n+----------------+---------------------+--------+-----------------+\n\nWe thank Marcelo Mora, Povilas Palunas, and the rest of the LCO staff for making these observations possible.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36311.",
"published": "2024-04-26T01:28:51.026769Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-26T01:28:51.026790Z",
"modified": "2024-04-26T01:28:51.034194Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6976,
"topic": "gcn.circular",
"uuid": "ce48be35-5ebe-4278-8f51-9d936ff762ba",
"title": "EP240426a: GMG optical upper limit",
"submitter": "Hop gcn.circular",
"authors": "wangbaiting@ynao.ac.cn",
"data": {
"date": "24/04/26 14:10:11 GMT",
"from": "wangbaiting@ynao.ac.cn",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36315"
},
"title": "GCN CIRCULAR",
"number": "36315",
"subject": "EP240426a: GMG optical upper limit"
},
"message_text": "B.-T. Wang, R.-Z. Li, J. Mao, L.-Y. Zhu, Y.-Z. Cai, J.-M. Bai (YNAO) report:\n\nWe observed the field of EP-FXT detection of the candidate conterpart EP 2406026a (Sun et al. GCN 36313) by the GMG-2.4m telescope at the Lijiang station in Yunnan Observatories. The observation began at 2024-04-26T12:37:20. No optical counterpart was detected within the EP-FXT error circle.\n\nThe very preliminary upper limit can be given i>18.7.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36315.",
"published": "2024-04-26T14:10:28.689015Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-26T14:10:28.689034Z",
"modified": "2024-04-26T14:10:28.694639Z",
"nonlocalizedevents": [],
"targets": []
},
{
"id": 6977,
"topic": "gcn.circular",
"uuid": "30961210-241d-4063-ba2d-84d79a491520",
"title": "LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations",
"submitter": "Hop gcn.circular",
"authors": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"data": {
"date": "24/04/26 14:38:58 GMT",
"from": "Ryan Foley at UC Santa Cruz <foley@ucsc.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36316"
},
"title": "GCN CIRCULAR",
"number": "36316",
"subject": "LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations"
},
"message_text": "A. L. Piro, J. D. Simon (Carnegie), A. Polin (Carnegie/Purdue), D. A. Coulter (STScI), M. R. Drout (Toronto), R. J. Foley, and C. Rojas-Bravo (UC Santa Cruz)\n\nreport on behalf of the Carnegie Gravitational wave ElectroMagnetic follow-up (CGEM) and the One-Meter Two-Hemisphere (1M2H) collaborations:\n\nWe have continued our galaxy-targeted search (GCN 36244, GCN 36267) for optical counterparts to the candidate gravitational wave event S240422ed (GCN 36236) using Teglon (Coulter 2021) with the LDSS-3 imager on the 6.5m Magellan Clay telescope. We obtained a series of 120-second i-band images targeting galaxies coincident with the 3D localization of S240422ed. We performed a preliminary search of the data by comparing to archival Pan-STARRS (Chambers et al., 2016) and DECaPS2 (Saydjari et al. 2022) images, and found no obvious transient sources near the targeted galaxies. However, we note that several images were deeper than the comparison images, precluding the exclusion of some faint sources detected in only the new images as transient sources. The images have typical depths of i~21.5-22.5 mag, varying with seeing and airmass.\n\nWe thank Marcelo Mora, Povilas Palunas, and the rest of the LCO staff for making these observations possible.\n\nBelow we provide a list of targeted galaxies (including those previously listed in GCN 36244 for completeness) and observation details.\n\n\n Galaxy RA Dec Filter Start (UT) Date (UT)\n86096 07:52:28.3 -25:55:06.4 i_Sloan 01:00:32 2024-04-25\n07534680-2656186 07:53:46.8 -26:56:18.6 i_Sloan 23:19:39 2024-04-23\n07543602-2134176 07:54:36.0 -21:34:17.1 i_Sloan 23:24:13 2024-04-23\n07550406-2137197 07:55:04.0 -21:37:19.9 i_Sloan 03:13:16 2024-04-25\n07552968-2203256 07:55:29.7 -22:03:25.4 i_Sloan 23:27:14 2024-04-23\n07560574-2254025 07:56:05.8 -22:54:02.0 i_Sloan 23:33:13 2024-04-23\n79057 07:56:17.0 -22:07:36.9 i_Sloan 03:26:51 2024-04-25\n07595685-2210083 07:57:41.8 -21:53:12.7 r_Sloan 00:06:20 2024-04-24\nESO561-004 07:58:18.6 -20:40:09.3 i_Sloan 02:33:12 2024-04-25\n07582363-2159463 07:58:23.6 -21:59:46.0 i_Sloan 23:38:36 2024-04-23\n79228 07:58:40.1 -22:05:11.4 i_Sloan 01:44:41 2024-04-25\n07585448-2217184 07:58:50.3 -22:17:15.1 i_Sloan 23:56:33 2024-04-23\n07585614-2220434 07:58:56.2 -22:20:42.9 i_Sloan 23:46:48 2024-04-23\n79263 07:59:13.4 -22:28:44.6 i_Sloan 00:00:08 2024-04-24\n79305 07:59:52.7 -19:47:48.3 i_Sloan 01:03:50 2024-04-25\n07595685-2210083 07:59:56.9 -22:10:08.0 i_Sloan 00:02:37 2024-04-24\n08000411-2741493 08:00:04.1 -27:41:49.0 i_Sloan 00:20:15 2024-04-24\n86114 08:00:19.0 -24:48:08.6 i_Sloan 00:23:34 2024-04-24\n08001933-2225390 08:00:19.4 -22:25:38.8 i_Sloan 00:46:04 2024-04-25\n08005056-2718507 08:00:50.6 -27:18:50.3 i_Sloan 00:28:13 2024-04-24\n08005453-2722597 08:00:54.5 -27:22:59.6 i_Sloan 00:32:12 2024-04-24\n08010965-2426127 08:01:09.7 -24:26:12.6 i_Sloan 00:36:45 2024-04-24\n86116 08:01:16.7 -18:22:40.4 i_Sloan 02:08:39 2024-04-25\n08011925-2545475 08:01:19.3 -25:45:47.2 i_Sloan 00:52:29 2024-04-24\n79455 08:02:23.5 -24:51:16.8 i_Sloan 02:19:21 2024-04-25\n85985 08:02:56.1 -17:38:41.9 i_Sloan 00:43:05 2024-04-25\n79513 08:03:05.2 -26:12:00.2 i_Sloan 03:32:54 2024-04-25\n08030545-2241003 08:03:05.5 -22:41:00.1 i_Sloan 00:39:45 2024-04-25\n79523 08:03:17.8 -22:21:44.9 i_Sloan 00:56:22 2024-04-24\n08032043-2438176 08:03:20.5 -24:38:17.2 i_Sloan 01:00:16 2024-04-24\nAT2024hdo 08:03:28.0 -26:00:43.6 i_Sloan 00:36:42 2024-04-25\n79567 08:03:56.2 -22:45:18.3 i_Sloan 01:55:28 2024-04-25\n79594 08:04:16.1 -22:50:23.2 i_Sloan 01:03:35 2024-04-24\n08041619-2250225 08:04:16.2 -22:50:22.0 i_Sloan 01:06:41 2024-04-24\n79611 08:04:30.8 -21:07:41.8 i_Sloan 01:10:47 2024-04-24\n08043558-2509271 08:04:35.6 -25:09:26.6 i_Sloan 01:14:23 2024-04-24\n08045252-2332340 08:04:52.6 -23:32:33.8 i_Sloan 01:17:46 2024-04-24\n08045440-2809421 08:04:54.4 -28:09:41.9 i_Sloan 01:48:13 2024-04-25\n79659 08:05:13.4 -28:17:53.9 i_Sloan 01:21:12 2024-04-24\n79662 08:05:16.7 -22:49:20.6 i_Sloan 01:24:38 2024-04-24\n08052595-1952404 08:05:26.0 -19:52:40.2 i_Sloan 01:59:05 2024-04-25\n86141 08:05:31.0 -22:40:00.1 i_Sloan 00:53:42 2024-04-25\n08054271-2019104 08:05:42.7 -20:19:10.7 i_Sloan 01:28:03 2024-04-24\n79738 08:06:04.3 -22:27:12.1 i_Sloan 01:33:13 2024-04-24\n79786 08:06:35.0 -25:11:21.9 i_Sloan 01:40:37 2024-04-24\n79842 08:07:20.3 -24:47:03.4 i_Sloan 01:43:57 2024-04-24\n79859 08:07:27.0 -21:30:47.8 i_Sloan 01:47:18 2024-04-24\n79872 08:07:32.2 -23:24:07.8 i_Sloan 01:50:35 2024-04-24\n08074766-1647407 08:07:47.7 -16:47:40.6 i_Sloan 01:53:41 2024-04-24\n79934 08:08:18.5 -18:41:07.5 i_Sloan 01:56:51 2024-04-24\n861462 08:08:39.1 -18:58:10.5 i_Sloan 02:13:20 2024-04-24\n79992 08:08:45.6 -19:59:04.2 z_Sloan 02:30:28 2024-04-24\n79993 08:08:46.5 -19:58:50.3 z_Sloan 02:33:25 2024-04-24\n79997 08:08:49.9 -24:31:20.2 i_Sloan 01:21:21 2024-04-25\n08085158-1850516 08:08:51.6 -18:50:51.2 i_Sloan 02:53:03 2024-04-24\n08085438-1539412 08:08:54.4 -15:39:41.1 i_Sloan 02:56:29 2024-04-24\n80022 08:09:02.6 -24:27:02.7 i_Sloan 03:01:36 2024-04-24\n80028 08:09:07.6 -18:11:58.8 i_Sloan 03:04:55 2024-04-24\n08091236-2434441 08:09:12.4 -24:34:44.2 i_Sloan 03:08:28 2024-04-24\n86157 08:09:15.1 -18:40:42.5 i_Sloan 03:11:52 2024-04-24\nESO561-018 08:09:15.2 -18:39:52.9 i_Sloan 01:07:11 2024-04-25\n80053 08:09:19.3 -18:28:24.8 i_Sloan 03:14:45 2024-04-24\n80060 08:09:24.3 -18:32:03.1 i_Sloan 03:18:03 2024-04-24\n80061 08:09:24.5 -18:27:47.4 i_Sloan 03:22:01 2024-04-24\n08095686-1812076 08:09:56.8 -18:12:07.7 i_Sloan 03:23:19 2024-04-25\n80133 08:09:59.7 -20:26:59.5 i_Sloan 03:25:16 2024-04-24\n80140 08:10:04.0 -18:02:03.5 i_Sloan 02:12:27 2024-04-25\n08103700-1811480 08:10:37.1 -18:11:48.0 i_Sloan 03:28:51 2024-04-24\n891963 08:10:51.5 -16:53:49.1 i_Sloan 03:29:49 2024-04-25\n80222 08:10:55.9 -18:05:15.0 i_Sloan 03:32:28 2024-04-24\n80239 08:11:02.4 -17:01:51.7 i_Sloan 02:05:32 2024-04-25\n80249 08:11:06.0 -23:41:21.3 i_Sloan 03:36:16 2024-04-25\n80293 08:11:35.4 -24:08:54.7 i_Sloan 03:36:36 2024-04-24\n3085162 08:11:58.4 -16:49:33.3 i_Sloan 03:39:56 2024-04-24\n80342 08:12:12.9 -17:00:38.9 i_Sloan 03:43:25 2024-04-24\n80350 08:12:16.7 -21:47:19.0 i_Sloan 02:15:48 2024-04-25\n08131151-2802346 08:13:11.5 -28:02:34.7 i_Sloan 03:46:47 2024-04-24\n80468 08:13:37.8 -20:59:46.7 i_Sloan 03:52:46 2024-04-24\n80539 08:14:21.3 -15:28:22.9 i_Sloan 02:26:22 2024-04-25\n906392 08:14:21.8 -15:47:45.0 i_Sloan 01:51:50 2024-04-25\n80596 08:14:50.1 -22:46:14.7 i_Sloan 03:55:35 2024-04-24\n909683 08:15:01.6 -15:33:07.6 i_Sloan 01:27:59 2024-04-25\n08150201-2253489 08:15:02.0 -22:53:48.7 i_Sloan 01:41:25 2024-04-25\n80646 08:15:17.4 -15:35:01.6 i_Sloan 01:14:05 2024-04-25\n80665 08:15:29.1 -15:44:02.8 i_Sloan 02:39:58 2024-04-25\n08153710-1720514 08:15:37.1 -17:20:51.0 i_Sloan 03:20:07 2024-04-25\n08161352-2130238 08:16:13.5 -21:30:23.6 i_Sloan 01:24:35 2024-04-25\n08163364-2039438 08:16:33.7 -20:39:43.4 i_Sloan 01:10:21 2024-04-25\n08164547-2036118 08:16:45.5 -20:36:11.7 i_Sloan 01:17:58 2024-04-25\n08171213-1832346 08:17:12.1 -18:32:34.7 i_Sloan 01:38:13 2024-04-25\n6dFJ0817278-1501 08:17:27.8 -15:01:33.7 i_Sloan 02:58:43 2024-04-25\n80844 08:17:29.3 -22:29:30.7 i_Sloan 03:16:45 2024-04-25\n900792 08:18:00.6 -16:13:59.6 i_Sloan 00:56:58 2024-04-25\n80880 08:18:05.8 -20:06:32.0 i_Sloan 01:31:19 2024-04-25\n920402 08:18:35.2 -14:45:11.0 i_Sloan 02:42:55 2024-04-25\n96401 08:20:29.1 -18:33:26.8 i_Sloan 03:01:57 2024-04-25\n6dFJ0821102-1813 08:21:10.2 -18:13:08.6 i_Sloan 02:36:25 2024-04-25\n08221434-2041541 08:22:14.3 -20:41:54.0 i_Sloan 02:54:43 2024-04-25\n81160 08:24:53.0 -23:13:11.7 i_Sloan 02:22:44 2024-04-25\nESO562-006 08:26:19.2 -20:50:51.6 i_Sloan 00:49:27 2024-04-25\nESO495-013 08:26:26.2 -27:21:36.3 i_Sloan 01:34:47 2024-04-25\n08262641-2721375 08:26:26.4 -27:21:37.4 i_Sloan 02:46:20 2024-04-25\n152509 08:27:44.4 -21:06:47.0 i_Sloan 02:02:26 2024-04-25\nESO431-011 08:28:47.3 -27:43:12.9 i_Sloan 03:05:46 2024-04-25\n\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36316.",
"published": "2024-04-26T14:39:14.159384Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-26T14:39:14.159409Z",
"modified": "2024-04-26T14:39:14.167216Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6973,
"topic": "gcn.circular",
"uuid": "9edd97f2-056d-4ca8-acd1-c02366002622",
"title": "LVK S240422ed: Further Swift-XRT followup of three sources",
"submitter": "Hop gcn.circular",
"authors": "P.A. Evans at U. Leicester <pae9@leicester.ac.uk>",
"data": {
"date": "24/04/26 13:13:34 GMT",
"from": "P.A. Evans at U. Leicester <pae9@leicester.ac.uk>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36314"
},
"title": "GCN CIRCULAR",
"number": "36314",
"subject": "LVK S240422ed: Further Swift-XRT followup of three sources"
},
"message_text": "P.A. Evans (U. Leicester), K.L. Page (U. Leicester), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), S.B. Cenko (NASA/GSFC), R.A.J. Eyles-Ferris (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), A.A. Breeveld (UCL-MSSL), S. Campana (INAF-OAB), M. De Pasquale (University of Messina), S. Dichiara (PSU), P. DâAvanzo (INAF-OAB), A. DâAì (INAF-IASFPA) , V. DâElia (ASI-SSDC & INAF-OAR), C. Gronwall (PSU), D. Hartmann (Clemson University), N. Klingler (NASA-GSFC / UMBC / CRESST II), N.P.M. Kuin (UCL-MSSL), S. Laha (NASA/GSFC), S.R. Oates (U. Birmingham), J.P. Osborne (U. Leicester), P. OâBrien (U. Leicester), M.J. Page (UCL-MSSL), G. Raman (PSU) S. Ronchini (PSU), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (U Tor Vergata, INAF) report on behalf of the Swift team:\n\nSwift has conducted follow-up observations of sources S240422ed_X61, S240422ed_X101 and S240422ed_X190, reported in GCN Circ. 36278. All three sources are now undetected with fading confirmed at at least the 3-sigma level.\n\nOn close inspection, we now believe that source S240422ed_X190 is not a real X-ray object. The XRT was operating at a higher-than-normal temperature when that object was detected and the image has an abnormally high background; further, the PSF of the source is not consistent with that expected for the reported count-rate, we thus believe this object can be dismissed.\n\nSource S240422ed_X61 was detected initially with a count rate of (8.3 +/- 3.0) x 10^-2 ct s^-1; in the latest observation it is undetected with a 3-sigma upper limit of 1.02 x 10^-2 ct s^-1.\n\nSource S240422ed_X101 was detected initially with a count rate of 0.10 +/- 0.03 ct s^-1; in the latest observation it is undetected with a 3-sigma upper limit of 1.05 x 10^-2 ct s^-1.\n\nBoth of these sources were also initially detected while the XRT temperature was elevated; however, there is no evidence of significantly increased background in those observations.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36314.",
"published": "2024-04-26T13:13:50.798754Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-26T13:13:50.798774Z",
"modified": "2024-04-26T13:13:50.806311Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6981,
"topic": "gcn.circular",
"uuid": "dbebf7ad-5a86-4895-a0bc-188fd9724762",
"title": "LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection",
"submitter": "Hop gcn.circular",
"authors": "Antonella Palmese at Carnegie Mellon University <apalmese@andrew.cmu.edu>",
"data": {
"date": "24/04/26 15:31:29 GMT",
"from": "Antonella Palmese at Carnegie Mellon University <apalmese@andrew.cmu.edu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36317"
},
"title": "GCN CIRCULAR",
"number": "36317",
"subject": "LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection"
},
"message_text": "Lei Hu (CMU), Brendan O'Connor (CMU), Antonella Palmese (CMU), Tomás Cabrera (CMU), Igor Andreoni (UMD), Keerthi Kunnumkai (CMU), report on behalf of the GW-MMADS team:\n\nDuring GW-MMADS DECam follow-up (Palmese et al., GCN 36245) of the LIGO/Virgo/KAGRA event S240422ed (GCN 36236, GCN 36240), we serendipitously observed the location of EP240426a (EP team et al., GCN 36313). \n\nIn our difference imaging relative to archival DECam images, obtained using SFFT (Hu et al., 2022), we recover the following detection within 5.2 arcsec of the EP240426a centroid prior to the EP observations. The transient has been reported to TNS as AT2024hhs (https://www.wis-tns.org/object/2024hhs):\n\n filter | observation time UT | magnitude (AB)\nDECam-z | 2024-04-24T03:15:28 | >21.08 (5-sigma)\nDECam-r | 2024-04-25T00:34:17 | >22.56 (5-sigma)\nDECam-z | 2024-04-25T02:35:12 | 21.01 +/- 0.10\n\nPreliminary forced photometry on our z-band image of this field from the first night of follow-up at 2024-04-23T03:05:18 show a possible faint detection at mag(AB)=21.41 +- 0.20, which is at the 5sigma depth limit and did not generate an alert in our pipeline.\n\nThe location of our transient is close to nuclear (0.36 arcsec). We cannot exclude variability due to possible AGN activity. We do not detect a transient at the centroid location of EP240426a, with a 5-sigma limiting magnitude of 21.4 mag in z-band at 2024-04-25T02:35:12.\n\nMagnitudes are not corrected for Milky Way extinction.\n\nWe thank the CTIO and NOIRLab staff for supporting these observations and the data calibrations.\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36317.",
"published": "2024-04-26T15:31:43.929739Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-26T15:31:43.929755Z",
"modified": "2024-04-26T15:31:43.933769Z",
"nonlocalizedevents": [
{
"event_id": "S240422e"
}
],
"targets": []
},
{
"id": 6982,
"topic": "gcn.circular",
"uuid": "dfa595be-7210-489c-8df9-198d62ecdf13",
"title": "GRB 240414A: NOEMA detection",
"submitter": "Hop gcn.circular",
"authors": "Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>",
"data": {
"date": "24/04/26 15:39:53 GMT",
"from": "Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>",
"urls": {
"gcn_circular": "https://gcn.nasa.gov/circulars/36318"
},
"title": "GCN CIRCULAR",
"number": "36318",
"subject": "GRB 240414A: NOEMA detection"
},
"message_text": "A. de Ugarte Postigo (CNRS/OCA & LAM), M. Bremer (IRAM), C. C. Thoene (ASU-CAS), J. F. Agui Fernandez (CAHA), S. Antier (OCA), S. Basa (LAM), M. Michalowski (AOI-AMU), D. A. Perley (LJMU), J.-G. Ducoin (CPPM) report:\n\nWe observed the field of GRB 240414A (Caputo et al. GCN 36083; Myers et al. GCN 36120; Cheung et al. GCN 36147) with the NOEMA interferometer, located at the Plateau de Bure (France). The observation, performed on the 23rd April, was tuned with sidebands at 74 and 90 GHz.\n\nWhen combining all the data, we obtain a weak, 3-sigma detection at the position of the afterglow (Schneider et al. GCN 36084; Adami et al. GCN 36085; de Ugarte Postigo GCN 36087; Dutton et al. 36097; Turpin et al. GCN 36101; Osborne et al. GCN 36102; Dichiara et al. GCN 36104; Pankov et al. GCN 36113; Siegel et al. GCN 36115; de Ugarte Postigo et al. GCN 36117; Wang et al. GCN 36131; Rossi et al. GCN 36228; Rhodes et al. GCN 36229; Giarratana et al. GCN 36231) with a flux density of ~55 uJy.\n\nBased on observations carried out under project number W23DI with the IRAM NOEMA Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).\n\n\nView this GCN Circular online at https://gcn.nasa.gov/circulars/36318.",
"published": "2024-04-26T15:40:11.390251Z",
"message_parser": "GCN Circular Parser v1",
"retracted": false,
"created": "2024-04-26T15:40:11.390277Z",
"modified": "2024-04-26T15:40:11.395499Z",
"nonlocalizedevents": [],
"targets": []
}
]
}
